They've earned the grief over a long period of time.
If they truly want to turn over a new leaf then they need to be prepared to accept that they will not get an immediate return from most, who will be suspicious that anything positive is a fleeting exception and hold the grudge.
If they are serious, then they need to keep it up regardless of whether they get immediate recognition. People will eventually come around.
In other words, if you are telling us if they don't get some positive feedback then they will return to their old ways, then that will just confirm the negative feelings and suspicion.