I hate it when you get a house track that suddenly gets an inappropriate diva on it for a chart remix. I'm thinking of something like Love Story by Layo & Bushwhacka. Not an amazing tune, but one that's totally ruined by the rubbish singing and sax solo - that wasn't in the original when I heard it in The End.
I had that exact experience - I remember hearing the piano break on Love Story when Layo & Bushwacka were DJing months before it came out, and it totally stuck in my head as this amazing record. I didn't know what it was until it got released, and I was really disappointed because it just didn'd sound the same.