The West Coast Customs tie-in to West Coast Racers is pretty cringy. I laughed pretty hard when that ride got announced. Not only is it a sponsorship, but the ride is actually themed around it and they missed the boat by about 15 years.
I think Steel Curtain might be king though. Again, the entire attraction is themed around it. And to make matters worse, it doesn't fit the park, and especially that area of the park, at all. Yeah, it's pure Pittsburgh and I'm sure the city's residents loves it, but it's so tacky.
But in the more traditional sense of sponsorship, I hated when Six Flags Over Georgia had Mindbender wrapped in Stride gum sponsorship. It was a shame to see such a fantastic Schwarzkopf defaced like that.