Boring county west of the Hudson. And that's where its stigma originates from: West of the Hudson. Given that Rockland kind of reminds real New Yorkers (Westchester/NYC/LI) of Jersey, people are inclined not to think of it as part of NY. Although Rockland IS no more north than Westchester, simply because the Thruway goes west before it heads north, that gives people in Westchester the impression they are going "upstate" into Rockland since they pass thru to get to places like Orange/Ulster/Sullivan County. Rockland has no walkability to it (no sidewalks, no interesting towns or neighborhoods) so is therefore NOT part of the real New York.
Anything in NYS west of the Hudson, as well as Bedford and up east of the river, should secede into the State of Upstate New York.