I have never seen them do the Hotdog Sound at Disney Junior Show over in HS. I have a 2 year old and we've seen the show a few times and were actually disappointed they didn't do it at the end like they always do on the show. But maybe they've changed it in the last couple of months since I have seen the show?
I know 'talking' Mickey sometimes will sing a few lines of it and does the Hot Dog dance with some kids during his Meet and Greet in MK.
Goofy over at Character Spot in Epcot has also done the dance with my daughter, his handler asked him to do it and he complied (but obviousy couldn't sing it like Mickey does.)