I've been watching a lot of L&H on YouTube, and I'm laughing at parts where I think "would they find this particular thing funny back in the 30's?" Also, when were the first dirty jokes in films, and would it have been acceptable to laugh at them?
While more can always be said, there is a good thread of discussion in this older thread which might be of interest, courtesy of /u/grantimatter and /u/lord_mayor_of_reddit, among others.