I think most Elves were suspicious of strangers in those times, especially Dwarfs. Take Lothlorien for example, it didn't exactly have a friendly reputation in the surrounding lands did it? Also, if you had Sauron Necromancing on your doorstep you wouldn't be too keen on visitors really would you?
I believe Thranduil was also some kind of relative to Thingol (nephew?).
Thorin's ancestors had had nothing to do with that nauglafring business, of course, but Elven blood is very thick, it seems.
Maybe Chathol-linn's "Elflocks" story in the fan writing section throws some light on why he doesn't like dwarves (or one in particular)
I don't think the Dwarves slamming shut the doors of Khazad-dum while Sauron's forces swept through Eregion would have adhered him too well with them either. I imagine Thranduil probably lost kin during this dark period of the Second Age while the Dwarves sat idly by.