In general I think people take an approach similar to the one you're taking, where the spray from the showerhead is deflected off the side of the shower. It's been a few years since I've done this personally, but my experiences (with Veiled and T. deremensis) were similar to yours: the animals just didn't seem to appreciate the experience very much.
In general I've had reasonable success with a few species (C. calyptratus, T. deremensis, and T. jacksonii xantholophus) with hand-spraying and controlling ventilation (screen works great outside here in Hawaii, or during the summer back in Michigan--less ventilation inside, during the dry winters is helpful in maintaining humidity).
For a really dehydrated animal, or a really large one with substantial water volume requirments I can understand trying the shower method, but I never had much luck with it, and stopped doing it after a while. Hand-spraying or using an automatic mister to spray the animal for a longer period (say 20-30 min), or something along those lines would, I think, work best for a lot of folks in a lot of situations.
Perhaps others have had better success using showers?....
cj
