Oh dear, only just seen this and cannot read the whole thing.
Just going on the title, yes they can and do appear pally with certain posters but usually it's the ones who are the most vocal, in touch with them the most and talk in the same sort of way ie blustery humour and some grasp of what it looks like from the other side. I suppose like shop assistants are nicer to you if you smile at them and treat them like humans, probably because you've worked in a shop yourself and know how crap it can be.
It can sometimes appear that they favour some over others...the problem can be that some regular reports you for something or has a pop at you, and someone new's on duty or they don't recognise you under a name change though they're of course well aware of who the reg is.
So you get a patronising email and think, hey wait a minute, what's so and so got over me? and then you reply to it v politely in the same language you've always used with them when you write them friendly little emails 
and they are like, Oh holy shit, we've pissed off another reg, but erm we can't back down now as we already told the first one we'd sort you out.
So they immediately have to try and be nice to both of you and it is all very embarrassing.
and so on and so on. And then they just pretend it never happened and after about 3 months you do, too. And move on.
They're just doing their best.