I was never particularly compelled to read GG fic specifically - it's just not a show I was ever fannish about, much though I loved it - but I happened across one by chance once as part of a multifandom femslash ficathon. Unfortunately that fic is probably the single best GG fic on the whole of the internet - perfect voice, absolutely brilliant use of all involved characters, heartwarmingly precision portrayal of the Rory/Lorelai relationship, and it seriously did sound basically exactly like the show. Which... my fannish beginnings were basically Buffyverse, and that particular mode of Joss-speech is tricky to capture as well, so I'm very used to allowing for stylistic differences in fic... at least, I usually am. I can't do it with Gilmore Girls, though. That first fic just set the bar too damn high.
I can pretty much always make an exception for crackfic, though. Which Dean/Lorelai kind of is by nature. ^^