1. Every Opening Post and replies contributing towards it are considered as constructive posts.Any other irrelevant posts are considered to be spam.
For example,if you ask "What's the capital of United States" and I say it's very hot today,it will be considered as spam.
2. Any posts made for the welfare of the community are definitely constructive,including giveaways.
3. Trolling is definitely non-constructive.
Example,you are selling 1 bitcoin and I offer you 50 cents,something which is not considerable at all and definitely a troll.
4. Very short replies like 'I know' , 'Okay' also make up non-constructive posts.
5. Making any posts with the purpose of increasing post count like posting too much in off-topic,especially when you recently joined a signature campaign is not constructive either.
1 - What about one-line answers? When they start to be spam? For example: if I answer "Washington", will it be spam? I think the signature campaigns say that one-word answer won't be paid, but in this case it gives the answer for the question
2 - OK.
3 - You should agree flaming and personal attacks too. Also personal discussions that end up killing the topic's theme(it's common on off-topic)
4 - It in some cases can conflict with 1. Another example: someone asks where he can find certain information, and I post with the link for the information
5 - Posting too much in off-topic is dangerous, specially if you recently joined a signature campaign. But in off topic there are useless topics and topics with really good discussions, some related to bitcoins(for example: one asking why you entered the BTC world). Think the best rule is only post the topics with good discussions, and if, and only if, you have very substantial things to add, or genuine personal interest about what is being posted(for example: I think it is legit discuss about future results of world cup if you made bets about the results.
What should be added:
6 - Read all topic before posting. Post if what you say have not been said in the topic.
7 - Read the subforum rules before posting.
8 - Make consecutive posts, one after another, is considered bad net etiquette, and I think that if you are part of a signature campaign will be considered spam, no matter how constructive they are. So don't do that in any hypothesis, edit your posts if you forgot to say something. If you want anwer more than one post, answer all of them in one single post.
Rule no 8 is actually pretty reasonable. You may add: even if you are creating perfectly fine coherent and constructive posts in large quantity you are probably spammer if you have paid signature.