I know this might not help but with that. There's a picture in "Sesame Street Unpaved" book of Bob with Bert in the forground taking a bath. It's not a very big pic but it's on Bob's profile. Your proubley right Mike. I would love to see this whole episode. (if there is one)I said this once before but I'll mention it again.
Either this album is based off an episode or maybe the made an epiosde based off the album.
It's hard to remember everything exactly but Bert's taking a bath and Ernie brings in the piano and eventualy everyone else you hear on that was on comes in and joins the fun, Much to the dispair of Bert.
I do have memory of them singing What's The Name Of That Song but can't remember anything else exactly other than Bert Obviously being very unhappy.