Most of the teachers I know have only been teachers for one year (I just finished my second year of grad school--some friends from undergrad got their credentials and just finished their first year of teaching) and I don't talk to them about their students very much, so I don't really have personal experience with longer term effects (or lack thereof).

I haven't thought much about it because I find the underlying sentiment sort of skeevy (if I give myself time to reflect this effect is often diminished I think) but also because I'm busy and not interested in teaching below university level, at which point selection effects kick in.