Two issues I see is pulling the seatpost/seat out, that's just asking for water to sit in the tubes and create problems. Other is pulling the trigger on the rinse hose, usually the water comes out fast enough to rinse without blasting the bike. Otherwise I've washed plenty of bikes off this way with no trouble. Lube the chain after and its quick and easy. I've checked under the seals after and haven't noticed water getting into the bearings being an issue.