Simply by buying an account at a rank higher than what you really are and then trying to claim a spot in one or more campaigns is effectively "abusing" sig campaigns.

They generally pay higher rates for higher ranking members with good quality posts. By short cutting that process and jumping straight to a "Sr. Member" account by buying it, you are effectively claiming to be a Sr. Member when you are in fact a newbie (Jr. Member at best after 1 month). That's definitely misrepresentation... and borderline fraud.

There is a reason why a number of the DT members tag account sellers and buyers.