Actually, having been through this myself recently, there ARE tests available out there for men who show no visible warts and are a-symptomatic.
After having my colposcopy and cryotherapy I wanted to make sure I wasn't going to re-expose myself to the virus with my husband. I asked my gynecologist if there was anything that could be done, and she said there is a test that is the equivalent of the colposcopy for men. It works the same way as a colposcopy, in that they swab the potentially infected tissue with a vinegar solution, but they don't take actual skin samples. If HPV is present, the solution will cause a reaction. My gyn said basically they take a cloth soaked with the solution and apply it to the potentially affected area. She also said that any general practice doc should be able to perform the test if asked. However, we haven't checked with our's yet to see if that's true....but the free clinic in our area does perform the test.
I thought this was really good news...at least in our case. If you are concerned, call your doc and ask about it, or call the local free clinic in your area and see if they do the testing. Good luck.