No, you should not.  Not even if they send you a message telling you their kids will starve to death because of your feedback (because that's a lie, as is any idiotic plea like that).

I've started tagging obvious merit abusers, because after thinking about this whole issue ever since the inception of the merit system, I've decided that abusing it is exactly what I was trying to fight when it got created--the ability of shitposters to participate in campaigns and thereby spread their Engrish manure all over the forum. 

It's so obvious, it's derp.  When these people get merits they don't deserve, they're going to rank up, earn more money in campaigns, and have incentive to keep doing this shit.  So I'm negging them, and I hope DT members keep doing it as well, AND I hope that the sig campaigns keep not accepting users with DT negatives.