Canada will deny you entry if you've been convicted of drug possession or DWI -- even if said conviction was a misdemeanor/civil affair if your home country. Why don't I see anybody complaining about that?
Well that's a silly question. No one is complaining about onerous entry requirements to Soviet Canuckistan because it's too cold to want to come here!
(No, it's really not that cold, come in summer, it's really hot. Don't bring your skis in July... again.)
On a clear disk you can seek forever.