From what I have seen in used sleds, condition will tell a lot. If it looks beat, chances are it is. The numbers on the odometer are only a guideline, check the rest of the sled for wear.
Whitedust mentions "Etek 2s is very well designed runs oil lines to crank so crank gets lubrication."
Not sure of the other manufacturers, but Polaris has been doing this for quite some time. If I recall correctly, Doo has in the past used bearings that didn't get any lube from the injection oil, but were pre-packed with grease prior to assembly?