We hired a car from AirAuto at Faro Airport in March 2010, this is the review that we have left;

DO NOT USE THIS COMPANY - They operate the classic scam whereby if you collect the vehicle in the dark they claim it is unmarked then upon return in the daylight they find some nearly invisible tiny scratches. Their man went straight to these tiny marks even though they were microscopic, he knew exactly where they were. They then charged us 300 euros. A complete scam DO NOT USE.