I usually disregard the odometer.
How a sled, especially a four stroke, was maintained is more important than mileage. My 05 Vector has had very good maint during its' 7500 miles, and I have seen other sleds a season old that I would not buy on a bet.
Best bet? Choose a sled, do the research on here for problem spots, and see if the owner addressed them. Look for dirty clutches, signs the skid was never lubed, that type of thing.