Deleting Records from the Recycle Bin only removes the crmentity record.
When a record is deleted from the recycle bin the crmentity record is deleted, but the related records are not.
When a contact record is created a record is added to each of the following tables (some other related records are also created such as an entry in vtiger_modtracker_basic)-:
1 x vtiger_crmentity
1 x vtiger_contactdetails
1 x vtiger_contactscf
1 x vtiger_contractaddress
The problem is that when a contact record is deleted from the recycle bin the record in vtiger_crmentity is removed, but all other related records remain. i.e. When a contact record is deleted from the recycle bin the data remains in the vtiger_contactdetails, vtiger_contactscf, vtiger_contractaddress etc.
Note, that this issue applies to all modules