It's a model, so the builder/owner can enter it if they want. Of course, temper that against the fact that most, if not any and all contest judges are not going to be fooled. No contest judge is going to give a pre-painted metal model high marks for finish, if they know it was painted in a factory. It's a 'checks & balances' situation. Even the best model from one of the 'Mints' won't get high grades for finish, no matter how it looks, if they know it was pre-painted. At least that's how it should be imho.