Some do, some don't. Mine states that "Your pet must be groomed and tidy -- pay special attention that nails are trimmed and smooth." My dog is groomed, tidy and has no offensive odor. If I had a stinky hound I'd bathe him, but I have a nice, clean border collie.
Some pet therapy organizations have ridiculous and/or onerous requirements. One group bans raw feeding, one requires the dogs' bandanas to be hanging in a certain way, others won't let members visit with people who belong to other therapy organizations. One I'd belonged to let their liability insurance lapse for 3 1/2 years without informing their membership(!).
I was careful when I switched organizations for the third time in 9 years that the one I joined suited me while remaining integrity in their program. I'm responsible enough to know if and when my dog needs to be bathed. I often make several visits a week; this week we're making 6. If I had to bathe my dog 12 hours prior to each visit I'd be bathing him every damn day. I'm more interested in the overall integrity of the organization than I am in stupid, prohibitive regulations that restrict conscientious volunteers from sharing their dogs.
ETA: I would absolutely honor a facility's request for a dog to be bathes prior to making a visit. That's why I don't participate in on of the local group visits to the local hospital's cancer unit. I understand their reasoning but it doesn't work for me, so I visit their hospice instead.
Both Celt and Megan had their certification, and we would visit the rehab facility once a month on the only night they had therapy dog visits, plus we occasionally visited elsewhere. We tended to the rehab because for some inexplicable reason, Celt could get freaked out by white-haired senior women - I *think* it may have had to do with something they used on their hair because it was only women with brilliant white hair. He'd look at them and get growly and fearful. So the rehab was great for us because he could visit without having to interact with older senior women with bright white hair! Megan, on the other hand, is an attention hound and was good with anyone and everyone.
The organization that we worked with did not require pre-visit bathing but just what Roxanne mentioned - neat grooming. But I felt uncomfortable after a while as, compared to most of the canine visitors, our dogs lived and worked on a farm, and so were exposed to high levels of "natural dirt and bacteria". I began to wonder if we should visit without bathing, and I was adverse to bathing my dogs if I could avoid it. My dilemma was solved when I needed to take on another responsibility that happened on the same evenings as the therapy dogs were allowed to visit, and so I let their certification lapse as we no longer were able to schedule visits.
I never realized there was so much variation in different organizations' requirements.
Sue Rayburn - Cleverly disguised as a responsible adult, but not the brightest firefly in the jar.
Celt, Megan, and Dan
"When the chips are down, watch where you step."
"The happiest people don't necessarily have the best of everything. They just make the best of everything." - author unknown