I'd have to say the old WHOW AM & FM in Clinton, Illinois before the station went dark.
I was on vacation listening to the radio. A young jock with some talent (if he had lots of direction) was on the air. The format would be variety-non-rock. They were playing album sides, all very scratched.
I don't know if they had a cue on the board but you could hear the jock drop the needle on the record. He played a whole Eddy Arnold LP and then a Vangelis LP (which skipped about 7 minutes until being discovered).
The jock, airing the legal ID had a bunch of people repeating it over and over for about a minute or so. Then into the National Weather Service audio until it began to repeat where upon the jock said, I think this is repeating what we've already heard.
When they'd plug in a PSA, the jock would hit the off switch on the turntable as a song faded (audio as it slowed to a stop and wowed back when the PSA was over). The PSA was on cart, and it wowed as a cart did with the old cart decks that had the engage level that brought the capstan up. The cart audio was as muddy as the Mississippi.
I spoke with the head of the Chamber of Commerce who told me the station had been 'falling apart' for years and hadn't run a commercial for years. It seemed they had CD decks but they were no longer working, so they were stuck playing old records on the one still working turntable. I cannot say this is entirely accurate as it came second-hand. I did hear one of those spots sold by the company in Chicago that sells via phone for stations around the country (you know, the guys that might change $50 a spot and the station gets 5-10% for airing the 'fill in the blank' copy they mail to the stations).
As I understand it, the station went dark and the new buyer had to provide a proof to get the stations. The stations have great coverage and location, so I felt they had good potential. I hope the station, under new ownership, is realizing its potential.
The station was so bad, my mini disc recorder in the car recorded a full 80 minute unscoped aircheck off the radio because I just couldn't bring myself to tune away.
So, what's the worst sounding station you heard?