No. I have sold a number of them in the past without any issue.
If you are in possession of one (legitimately) and are considering to sell it, then I would suggest that you somewhat be careful in screening potential buyers in order to have a good amount of certainty that it will not be used to help a scam, although the new trust algo makes it a lot harder for default trust (network) accounts to manipulate someone's trust rating.
The new trust algo also decreases the value of default trust accounts (as has the general expansion of the size of the default trust network).
How much do they go for?
I'd rather not disclose my finances specifically, however they sold for several bitcoin on average. It is pretty rare that a default trust account comes up for sale, besides the ones that I sold, the only other one that I can think of was a hacked account that was quickly restored to it's rightful owner. I know there was at least one additional one, although I don't think it was ever listed publicly.
