I'm interested to see what others say, but the little bit that I've read on the subject seems to always refer to gels and not creams. I'm sure that there are similarities between the two, but I don't know enough to comment further on that.
From what I've read about the gels, a lot of testosterone remains on the surface of the skin after the alcohol has evaporated. The alcohol is what allows the transdermal testosterone to penetrate the skin, so once it is gone(~10min) very little of the remaining testosterone is absorbed. A lot of it winds up on clothing. Numbers vary study to study.
Keeping the application site covered by clothing will prevent the test from transferring to your partner. Washing the application site will also prevent this(prevent detectable elevations in blood levels), although it doesn't remove all of the test from the skin. The studies I read did not specify if soap was used. Washing clothing doesn't remove all the test from clothing either. As stated though this is with gels that use alcohol as a vehicle for the test to be absorbed, so very little of the residual testosterone if any is absorbed. Creams, I don't know.
We have separate laundry, towels and luffas. I wear a shirt at all times until I've showered. I thoroughly scrub the application sites and rinse well. Two years of this and my GF has had no symptoms of too much test in her system, but her blood levels have not been tested.
Still, I often wonder about what happens to all of the residual testosterone that doesn't get washed off my skin and laundry. It's probably all over the place in trace amounts, and concentrated on certain areas like the couch and bed. What affect does this have over years and years? I don't know how well the controlled studies represent the reality of the situation.