Scammers can send PMs to invite you to buy their on-sold accounts. Buying accounts are discouraged (see below rule).
18. Having multiple accounts and account sales are allowed, but account sales are discouraged.
With the hype of market, I think account sellers will wake up and try to sell their accounts. Those accounts can easily be detected by their changes: email changed, password changed, woke-up after long period of inactivity, post gap between some years, suddenly apply to join campaign after those changes appear.
It is when you successfully buy account but during the process, you can be scammed too. Scammers can ask buyers (you) to go first, and they will run with your money while you don't have any account in hands. It is the worst situation but in better situation, your bought account can be useless when detected and painted with red trust.