This is the character who made his only major appearance in Operation: D.O.G.F.I.G.H.T. He did seem like a friendly old man at the start, but later, it was revealed he's evil. He pitted Hoagie and Kid against each other because all he wanted to do was destroy everything that makes/sells chilli hot dogs because his customers kept coming in with chilli dogs, accidentally leaving them on his clean counter-top or the chilli dribbling from them.
I've been making a more careful think about Mister Washer lately. When you find out his true intentions, by which I mean destroying anything and everything that makes/sells chilli hot dogs, and why those were his intentions, you can't help but wonder why he didn't ask the guy with the hot dog stand outside to move elsewhere, or better yet, put up a sign in his shop window that says "No Food or Drink allowed".