When it seems like an experiment that's been cited does not provide enough support for the interpretation given, remember that Scientists are generally pretty smart. Especially if the experiment was done a long time ago, or it is described as "classic" or "famous". In that case, you should consider the possibility that there is more evidence that you haven't seen.

This is a potentially dangerous assumption. There are cases of entire scientific fields being derailed for significant periods of time because everyone assumed that and hence no one bothered to check.