> after I realize what's happening, I tend to take a little longer for each reply so they figure out it's faster to just do the research on their own most times.
Agreed, and I do the same. They still get a courteous reply, but they also feel a little "pain" when they don't get a timely answer - an effective teacher.
They're usually pretty courteous in their interaction, which makes it all the more difficult to be "rude", in my case, by adding an exponential falloff in response times - after I realize what's happening, I tend to take a little longer for each reply so they figure out it's faster to just do the research on their own most times.