Overall I find Amtrak crews more genuine than flight crews, who seem more scripted and stilted. This can cut both ways.
Truly terrible flight attendants: maybe 1 per 100 flights. Truly terrible Amtrak attendants: maybe 1 per 25 rides. Having said that, I've encountered some of the most professional and genuinely friendly people in the travel industry aboard Amtrak trains.
Amtrak is really a world of extremes. Report the bad ones, commend the good ones, and perhaps the internal personnel process will eventually arrive at the right answer. (Or attempt the viral route; YouTube video/audio of particularly unprofessional behavior tends to gets noticed by the top brass!)