Service.dll

TryDelete(entity)
 new Guard()
   .Check(...)
   .Check(...)
   .Check(...)
   .Report();

DeleteEntity(entity)
  TryDelete(entity);
  // ... deleted

From controller point of view I can do:
When request for delete an entity

public void RequestDelete(Entity entity){
   try{
      Service.TryDelete(entity);
   }catch(GuardSpotException ex){
      // extract detail error summary
   }
}

public void RealDelete(Entity entity, string token){
  try{
    Service.Delete(entity);
  }catch(GuardSpotException ex){
    // extract detail error summary
  }
}

it just all POCO no additional learning required.

I have ever used similar thing(DBC) http://www.codeproject.com/KB/cs/designbycontract.aspx, but not for validating models.