I find it highly annoying that this merrit system is still around.
It is supose to be stimulating people to make good quality posts or topics, but i doesnt seems to work this way.
There were some times, I was against the merit system like you are right now. But now I see things differently: merit is the measure of how other people pay respect to you. Don't be over obsessed with quality, just join topics, give your opinion with and other will merit you if they find your post interesting, useful or just as simple as you're putting effort to it.
About merit selling, those sellers and buyers will be punished once they're are spotted. And high ranked members posting trash, well like you said, life is unfair and you've living with that, right?