I think theres an easy solution.
Threads should more rep oriented in the first place. Example:
[Request] *insert whatever* links on megaupload
1st Post: Can someone please find me links for *whatever* on megaupload?
1st Reply: I found 'em. I will post after you rep me.
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Case 1: User reps, person helps and posts.
Case 2: User reps, person does NOT help. (If this is the case, PM me and I will personally deal with the case, so as to not burden other mods)
That way, rep is always given when helping, and in case of any mishaps, I'll neg wise guys and give an infraction. Note that if the person *tries* to legitimately help, the rep remains. In case of disagreements, I'll solve the problem.