To be clear, selling a domain that has issues (IE- receiving a C+D) and not telling the buyer leaves a nasty door open.
1- You are still liable to the TM holder, even though you no longer own the domain. You are also subject to any and all actions as if you still owned teh domain (monetary damages, fines, legal fees)
2- You did not have the rights to sell the domain, thus, you fraudulently sold the domain to an unsuspecting buyer. This means the buyer can come after you for for monetary damages, legal fees (both against you and possibly against the TM holder if they come after him).
So it is not a good practice to do so. You violated TM law and are still liable for all damages and penalties. You are not absolved from your actions.