I would hope most could separate the good from the bad apples and keep an open mind. I can easily pick out medics to stray away from.
The blatantly bad medics that should never have gotten a patch are obvious. I see students all the time talking about how great X and Y medic are because they did this or that. I cringe knowing that many of those medics couldn't tell VT from asystole, or that whatever the student is praising them for is something incorrect. Without the knowledge, you don't know what you don't know. If they just fake it to make it, you may not catch on because they are confident despite their ineptitude.