Were you politically aware in the later 90s? Look at what happened with Clinton. There was proof of any number of things he did. It didn’t make a bit of difference. Clinton was great at having one scandal distract another scandal.
The difference is having someone like Trump blasting it out there and getting past the media filters. The Donald does it by being too irresistibly over-the-top to ignore. A large number of people won't take him seriously, but he may be able plant enough doubt in the minds of the mushy middle to make an impact.