Not everybody...
http://www.freep.com/money/consumer/guide2_20000702.htm states:
"What does MSU bug expert Walker use?
Deet.
"There are lots of different commercial products," Walker said. "The most effective ones have deet."
Walker said he uses deet on his two children, ages 3 and 5. He uses a concentration around 6 percent but uses a higher concentration for himself.
"Deet has an outstanding human safety record," he said.
Consumer Reports also found strong deet products to be effective. Among the products it tested, the most effective were Amway HourGuard12 and Off! Deep Woods for Sportsmen.
Off! Deep Woods for Sportmen, which is 100 percent deet, kept mosquitoes from biting for at least 11 to 12 hours. It kept ticks away for at least 4 hours.
Amway HourGuard12, which is 33 percent deet, kept ticks away for at least 9 hours.
BugOut, a 15-percent deet aerosol, worked for at least 4 hours against mosquitoes and at least 2 hours against ticks.
Avon's Skin-So-Soft Bug Guard did not protect Consumer Reports testers at all. Mosquitoes attacked at the first opportunity."
Please note that Avon do NOT call it a 'bug guard' and that name has been appended by the writer of the article I have quoted. Avon take pains to stress that it is an after-bath moisturiser and not an insect repellant.
Many university-research-based controlled tests have ended up with the same results - if it DOES work for some people, they don't know why.
I only know that it brings me out in an awful red swollen rash, DEET doesn't.