Just curious; what types of posts would count as spam? Like the obvious "

" and "nice post" don't count as constructive, but even if a post in on topic and relevant, is there a general minimum word/character count required for it to not be considered "spam"? Or would someone in a sig. campaign just post as they normally would?
Campaigns can have their own definition of spam.
Mine for instance won't pay below a certain number of characters.
Some also look at your post quality, if you are informative and constructive for instance.
Posting as you normally would should be OK.
Also is very important time of posting. Some campaign managers don't accept users that the difference of time between their posts is only few minutes.