(This is just one journalist's opinion.)
I read, watch, and listen to A LOT of NFL-oriented news, but I never hear or read anything about other teams' fans (with the exception of maybe Eagles fans) being as scathing as the Cleveland Browns fans are.
Yes, I am one of those condemning Browns fans too, but any professional NFL player or NCAA football prospect should understand that playing in Cleveland has to be one of the hardest places to play in the entire league because the fans can be so hard on the team.
Here are some example of Cleveland Browns fans being extremely judgmental over the years:
1. Cleveland fans throwing anything they could get their hands on onto the field in the late 80s. (snowballs, batteries, dog bones/biscuts, etc.)
2. The Bill Cowher signs blanketing the stadium last year during home games.
3. Cheering for injuries to QBs Derek Anderson and Tim Couch.
4. Throwing plastic beer bottles onto the field during a game, a few years back, thus causing the Cleveland Browns front office to ban plastic bottles at Cleveland Browns Stadium.
5. Browns fans constantly chanting a backup player's name when a starter does not perform.
6. ESPN analysts commenting on how Browns fans' chanting controls team decisions (cough, cough, Trent Dilfer, cough).
7. A stadium that is almost completely empty before the end of a game during home loses.
Honorable Mention: The Bengals fans acting out during a game causing Sam Wyches' "public service announcement" to Bengals fans in Cincy saying, "You don't live in Cleveland..." (Because Bengals fans were throwing items on the field like Cleveland fans did.)
These are the few that I could think of off the top of my head.
In my opinion, there are no fans more passionate than the Browns fans, but unfortunately, we are also very critical of our team because all we want to do is win games, be competitive, and get to the playoffs.
If that's a bad thing, then I guess I will be extremely nitpicky of my team year in and year out until we can consistently win in the NFL.
It's just part of being a Cleveland Browns fan who loves his team and just wants a winner, and I accepted that a long time ago.