How it was perceived is more of a pop culture question that's difficult for me to answer, but I can answer whether "disciplining" one's wife was acceptable in the 1950's. The answer is that it was not, although prohibitions were not as uniformly enforced as today and police and courts frequently viewed cases of domestic abuse as private matters between a husband and wife. (i.e. it's illegal, but up to the wife to leave if she thinks it's intolerable). By the 50's laws allowed women to seek divorce for abuse, and laws were on the books making it illegal, even if they weren't as frequently enforced.

Tennessee was the first state in the Union to make spousal abuse illegal. They passed a law prohibiting the practice in 1850. See this law review article although it's not clear how frequently it was enforced. Other states followed suit and by the 1920's every state had a law prohibiting domestic violence cases. Although, again, societal attitudes have a heavy bearing on how laws are actually enforced. See this article from the STanford Law review which cites State v Taylor, a Louisiana case from 1994 where the Trial Court refused to order a woman to testify against her husband in a domestic battery case, and the judge, on the record said "I think if this woman's crazy enough to want to get beat up by her husband within an inch of her life and she wants to go back and marry him that's her business." It was frequent that officers might be called to the scene of a domestic violence incident, but see the issues as a domestic matter, and their "role" as merely keeping the peace. Sometimes telling the abuser to go and get a hotel for the night, or asking the woman if she wanted to go stay somewhere, and leaving the matter at that.

This same time period is when Courts began to recognize that a husband's had no "right" to legally discipline his wife. At common law this had been called the "right of chastisement." In 1816, Tapping Reeve, writing America's first family law treatise, wrote that while "it is not to be denied, there are to be found brutal husbands who abuse their wives, the right of chastising a wife is not claimed, nor is any such right recognized by law." IN 1871 in Fulgham v Alabama the Alabama Supreme Court ruled that Fulgham had no legal right to physically discipline his wife. It might be notable that in this case, Fulgham was an african american man and a former slave who was discovered whipping his children by his wife, and when she objected, he used the whip on her as well. Another opinion from Masachusetts in 1871, COmmonwealth v McAfee, ruled "beating or striking a wife violently with an open hand is not one of the rights conferred on a husband by the marriage, even if the wife be drunk or insolent." Other opinions from Kentucky (1883), Texas (1875), Mississippi (1894) followed suit. It might also be noted in the McAfee case, McAfee was charged with manslaughter for killing his wife, and was arguing his criminal charge should be dismissed because it had been his "right" to beat her, so the case was to extreme it couldn't escape notice.

Outside of the criminal realm, the women's rights movement in the 1850's, onward also pressed states to adopt laws that allowed women to divorce husbands for cruelty or abuse. This, again, gradually occured between the 1850's and the 1920's

Getting back to societal views, and actually how it was treated. It was a second wave of domestic violence action in the 1990's that began a true legal push to force the court and police to stop viewing domestic violence as a "private matter," between the parties and as a crime worthy of arrest and punishment. This of course led to the violence against women act in 1994 and other laws.

So, in the 1950's, ricky spanking lucy would have very likely been illegal under the law and not accepted, but at the same time, in the 1950's it's quite unlikely that he would have been arrested and charged for a crime.

Going to how it's viewed. This sociology post discusses this in some detail. It references that part of the dynamic of the show was that Ricky was Cuban and Cubans were seen as having a more patriachal culture, and Ricky interacting with his outspoken wife was part of the humor of the show.

I haven't been able to find any real reaction to it in time, but it seems that in context this was somethign that was seen as "wrong" at the time, but not so serious that it couldn't be the source of humor, at least in a "light" form, not a "serious form" that it might have been if Ricky were to have come home and given Lucy a busted lip or a black eye. That would have been a behavior that many more people would have recognized as serious.

It's hard to say whether it was an accepted practice in real life. There are an extraordinary number of newspaper articles alleging that a judge here or there had determined that wife-spanking was fair, or that women in this or that town had formed a club for wives who approved of being spanked, but historical newspapers must be interrogated as primary sources - we have to analyze the bias they show, and not assume that they're basically and objectively factual, particularly when it comes to articles supposedly from other regions (such as a story set in Des Moines, Iowa, that's been syndicated and reprinted in Sacramento, California). In many cases, they seem to be completely fictional. Domestic violence was of course as much of an issue as ever in the past - as /u/BigBennP's answer makes clear - but it most likely involved the kinds of abuse we would expect to see today.

Night Worker's Right to Spank Wife Upheld

Sudbury, Ont. - The right of a night worker to spank his wife if breakfast isn't ready when he comes home was upheld by Magistrate J. S. McKessock. The judge dismissed an assault charge which Mrs. Paty Winters had brought against her husband, Edward. Winters testified he came home from the mine where he is employed and found no breakfast ready. His wife came downstairs and prepared it. He followed her back to the bedroom and scored three hits with a flat palm, he said.

(Salamanca Inquirer., November 20, 1936)

Husband May Spank Abusive Wife

Joliet, Ill. - A husband has the right to spank his wife if she makes him scrub the kitchen floor and then throws a flat iron at him for missing the corners. So Justice of the Peace McCowan decided when Joseph Selzniak's wife charged him with beating her.

(Fayetteville Bulletin., April 06, 1923)

A Pennsylvania judge has ruled that it is all right for a man to spank his wife if she doesn't "obey," from which we take it that the judge is not a married man.

(Canton Commercial Advertiser., February 05, 1935)

A lot of these news stories focus on a judge ruling that spanking was okay by virtue of his finding for the husband in a domestic violence case, ignoring the fact that there may have been other circumstances affecting the ruling - and this fabulous Pictorial article on this issue points out one 1924 case where the newspaper reported in a jolly tone that a woman was spanked for having her hair bobbed, but the actual court documents show that he punched her instead. So in the end, even if we accept all of these syndicated pieces as being real records of court cases, it's still up in the air whether or not they really involved spanking at all.

What we can say, however, is that a man spanking a woman he loved or would be in love with was a trope in pop culture in the early to mid-twentieth century. Representations of independent or aggressive or aloof women being dominated by their love interests (and loving it!) in a broader sense were all over the place: the proper romantic relationship might have playful banter, but the woman did not try to take control in a serious way or even be more skilled than her husband or lover, except in acceptable womanly pursuits. For a more hands-off example, the real Annie Oakley beat Frank Butler in a shooting match several years before they married, but in Annie Get Your Gun (1946), she deliberately loses to him in order to convince him that he's better than her, so he'll come back to her romantically. But there are entire websites devoted to pointing out scenes of spanking in mainstream films (here's an example), and as you can see, it happened in a lot of movies through the 1930s, 1940s, and 1950s. A female character stood up for herself, or insulted someone, or got in the way - there was always something that made her "deserve it", it was never used purposelessly - and in response, someone turned her over his knee and beat her as she struggled and gasped. The blog Vanilla Spanking documents a number of spanking scenes and the effects they and their rehearsals could have on the actresses involved here, and a good number of examples of films in which Maureen O'Hara was spanked here. (Honestly, the best source of information on this trend seems to be on fetishist websites - gender history scholars have not yet mined this rich vein.)

All of this reflected public uneasiness with changes in women's position in society. While activists had been working hard throughout the nineteenth century to give women more rights and opportunities, it's the early twentieth that saw young, unmarried women increasingly entering the workforce in white collar and retail positions, and then taking over both the blue and white collar worlds during World War II (more on this in my answer to Why is WW2 considered to be a major catalyst in the advancement of women in America when they had been a large part of the workforce since factories became mainstream?), having more freedom to engage in romantic and even sexual relationships, and of course getting the right to vote. Smoking and obvious cosmetics were creeping up the social ladder. Gratuitous spanking scenes in movies and television reinforced feminine powerlessness and childishness in the fight against change.

For those of us not familiar with I love Lucy, is there a video of this?

Can I piggy back off this with another “I Love Lucy” question?

How controversial was it to have an interracial couple on tv?