There's definitely been an increase in the requirements to be awarded the Medal of Honor. I believe there was a "clean up" of about a thousand names when they removed awards that were considered 'unworthy'. People like Buffalo Bill had his taken away (although posthumously reinstated in the 1980s).

To put it in context, there have been 3,530 medals awarded and 1,523 were during the Civil War. That's more than the entire 20th Century combined.

If you want some really questionable awards for the Medal of Honor I'd start with the Battle of Veracruz. It triggered a new way of looking at medals in general and is broadly considered a turning point for the Medal of Honor.