Let's have a go at this.

So, let's abandon for a moment the idea of "neutrally." There be dragons. Abandon all hope ye who enter here, etc. In reality it's an interesting question in its own right but a question of objectivity in history is really its own thread and I don't want to get bogged down in it here.

If you look at the historiography of the Soviet Union as written by "western" scholars you generally see the sort of "cold warrior" attitude which was hyper critical of the Soviet Union until the 1960s. This is often referred to as the "Totalitarian" school. Robert Conquest, Richard Pipes characterize this point of view pretty well. Their histories are very much about criticizing the Soviet regime, emphasizing the totalitarian nature of the Soviet Union, its desire for conquest and empire, and so forth. The things they criticize the Soviet Union for are usually understandable, but their laser focus on politics leaves something to be desired, theoretically, in my opinion.

In the late 1970s and 1980s some scholars started saying, wait a second all this emphasis on totalitarianism has kind of stopped us from actually looking at what people's actual lives are like over there. Describing the Soviet Union as "totalitarian" sort of gives the impression of everyone wear the same blue/grey outfit and just sort of trudging along. They started asking - well, what is life like? Sheila Fitzpatrick is usually associated with beginnings of this school, which has become known as the "revisionist" school for their desire to revise how Soviet history was being written. In essence saying that social histories needed to be written, not just political histories. Although they've often been criticized as defending the Soviet Union or brushing aside oppression, in my judgement many revisionists are just as critical of Stalin et. al, at their totalitarian school brethren, just from a different angle.

I think the social histories written in the 80s stand up substantially better than the totalitarian school histories written earlier in the century. But that isn't a reflection so much of them being "more neutral" per se, as it is a reflection of the development of historical theory over the past 30 years or so.

Likewise, by the time the 90s roll around the cold war is over and from a historiography standpoint the field has continued to change some, rolling with the changes in the field of history at large, but that's really outside the question asked here.

The other half of your question is interesting, but I'm not sure I can really answer it. I'm really not familiar with Soviet scholarship on American history to be honest. Perhaps someone else can come and say something more about that.

How could you tell? What defines viewing something a Neutral (not saying there can't be but you need to clear this up a little)?