Perhaps you could alter your setup (all of your SmartLists) to only read tasks from specific lists. Then when you came across certain tasks that meet the criteria that you mentioned you could move them into a regular, non-dynamic list called "No Point". That way they would effectively be removed from your system because none of your SmartLists would look in that list.

Alternatively, you could create a secondary RTM account, send the offending tasks to that account and delete them from your main account.