What's your script for...?

Though I know this is an issue for many sitters, I have yet to experience a late pickup that was not due to a completely legitimate reason.

Because I work full time outside my home, as well as having many other commitments in the community, I need to work out very specific times with clients up front. For example, I may say, "I'll get home from work tomorrow at 3:30 but will need to leave again by 5:00, and will not return from that outing until 8:00. When will it work best for you to pick up Boomer?" People have been very respectful of my time.

Then again, maybe I'm just lucky.

I really like how you've put it. It's direct and clear without being confrontational. Like Carmen, I haven't had anyone take advantage of my flexibility yet--the occasions someone has been late it was out of their control or at the very least they gave me advanced warning, an apology, and a new ETA. I think being clear about your expectations up front will save a lot of hassle down the road. When I set up pick up/drop off times I let the owner know if there is anything in my schedule which restricts when I'm available right up front, and I won't schedule a pick up or drop off within 30-60 mins of another obligation to allow a little wiggle room for someone running late.