But to my more broad of a point, the ultimate reason why someone will sell their account is because they have some need for money. If someone is in need of money, has a valuable account, but is unable to sell it, then there is a chance they may use their valuable account to try to scam someone.
A loan is another possibility. I haven't surveyed the Loaning section in quite some time so I'm not sure how many active loaners would accept an account as collateral but I'm sure there's probably still a small portion that will do so. I know that a loan would probably give the account-holder an amount less than what they will get if they sold/scammed but it's still probably a significant amount.
I would also point out that when someone buys an account they are investing money into that account. If someone who buys an account and starts to scam/spam, and does not recover their initial investment, they will lose money, so they have incentives not to do this.
True, but have you seen the types of posts that pass for constructive in some campaigns? There's a lot of spam out there: agreement posts, reiteration posts, "lock the thread" posts, missing information posts, etc.
There are also users that post redundant information (I might be a bit of an example since I tend to wander and use some rhetoric occasionally) on threads just so it will appear to be constructive, spanning multiple lines. Other offenders may post about subjects to which they have no knowledge of. e.g. mining, bitcoin dynamics, economics, technical details.
These usually allow a spammer to reach ROI quickly. As for scammers, they'll build the account up and then collapse it. Or alternatively, scam a newbie - new additions to the forum may ignorantly trust the rank system, thinking it to be proportional to the level of trust. Scammers and spammers can exist on the same account concurrently. They probably all follow the same methodology: join a signature campaign, post garbage and then see what they want to do afterward. (Continue or scam)
