All of my dogs do that EXCEPT my Yorkie!! The others come in to get pettted and have their ears scratched, but Dublin only comes in to play with the other dogs (who want nothing to do with him as long as there is human attention being doled out).
I think they just know that they have a captive audience.
I have one of those floor to ceiling showers, and Dublin does like to come in and drink. I use the handheld shower head to spray in his direction and he drinks from it like he was at a water fountain. When I first did it I thought he would run, now it's become a regular thing with him.