Since you asked, and only since you asked:
310214 - Many posts seem borderline incoherent. I would deduct a large amount of them if you paid him anything at all.
28364 - Mostly posted links to articles. I guess these could be useful. However the couple of articles I checked out seemed pretty marginal - basically his blog posts? Maybe pay and not invite back?
105473 - Really minimal quality posts.
152305 - Given your current guidelines I think you may have to pay him for some posts but certainly not all. Some are just an addy!
152501 - A lot of posts were outright duplicates, again, some may be legit but certainly not all.
244243 - Some legit posts.
Looking through these I realize it is harder to classify than I thought it would be. More props to Micro for going through so many and trying to help you out. My bottom line is that it is your campaign and if you don't think you should pay someone then you shouldn't.
I have posted many times
HERE and
HERE for example about my concerns of people posting marginal crap to get you to pay them and therefore drain your ability to continue the campaign. I love this campaign and have not left even though given my posting profile I could have made more with one of the other guys. I would strongly encourage you to expand the list of posts you wont pay for as many of these seemed to pass the +1, trolling, and no image basic criteria, yet were almost wholly worthless. I'd also not count all posts made in the off topic thread, but that is just me.
Basically don't feel obligated to pay people who are just abusing your good nature, or at best, pay them and then decline their participation in the future.
Good luck and thanks.