Since Valerie's moving in, it was finally time to get it fixed. Today I had the plumber from Union Jack Plumbing come out. He's British, and the company slogan is "The British are Plumbing! The British are plumbing!". You can't beat that. He was really nice, knowledgable, and...
he fixed the slow drain in about 3 minutes.
He stuck a vacuum down the drain and sucked up a shampoo bottle cap. After that it worked fine.
"So how much did that other bloke charge you for failing to fix anything?"
"About 60 dollars I think."
"I hate that."
The drain was still not draining as fast as he thought it could, so he stuck the snake down it anyhow just to be thorough. When it didn't improve anything he didn't charge me for its use.