Loud fans after repair by Apple
I've been using Macbook Pros for four years now, the one I'm using now (late 2010) is actually my fourth, and I've had loud fan problems with all of them. However, I've got the feeling that they're acting just fine in the beginning, constantly running on 2000 rpm and only spinning up on real heavy work load, but each time I take an MBP into repair and get it back the fans start acting all weird. I should probably mention that I've had warranty-related repairs with all four MBPs, two of them actually being replacement machines.
Could it really be that the geniusses mess it up every time? I heard that unnormal fan behavior could be related to incorrectly installed heat sensors or thermal paste on the cpu. This time, I got my screen replaced as it was having uneven backlighting and some coloring issues. Could it be something went wrong during the exchange process?