Canon Lens Check-up

I keep reading about good copy's and bad, sending in lens for checkups etc.

When you buy a used lens, then have to send it to Canon for whatever reason, how is the service? does it take awhile? if you have them do one of the checkups people speak of, does the cost make you wish you would have purchased a new lens?

So I wonder, if you get a good deal on a used Canon lens is it a hassle to get Canon to do minor repairs?

Canon seems to have gone to a fixed labour charge, at least here. Best is to buy the used lens either from a reputable store like KEH or Adorama that will take returns if you are unhappy with it, or from Craigslist where you can try the lens out yourself before buying.