Here's an example of an email I get asking for help this morning. No way I can just make this stuff up. I could also send you an example of one where a shop told them that the plastic gears are worn out inside. I don't have to tell you that there is no plastic inside.
"Hi Jim, As you can imagine, I found your email address on Sheldon Brown's web page, which in turn I found via a Google search. I have a Shimano RSX 7-speed shifter that sticks. It's my fault, I didn't ride the bike for seven years. I took the bike to my local shop, and they sprayed a bunch of WD-40 or similar into the shifter, which now works part of the time. I was wondering if you could tear it down and get it going for me? Actually, I should probably send the pair; the other 3-speed shifter has allegedly been fixed, but I'd feel better if you would do that one also. Regards, - ****"