For $150 the geek squad at Best Buy did absolutely NOTHING to reduce the slowdown problem I have with my computer, AND after promising they would not delete anything without asking, they permanently trashed a folder full of stuff I wanted.
They ran a full suite of software to clean up the registry and remove unneeded files, but it did not make the slightest difference to my problem. This is not a subjective off-the-cuff "feeling" it is a statement based on two complex processes I run, one I/O bound, one CPU bound. Neither one of them ran even one second faster after their "tuneup"
Lucky for me, I had a CD backup of my files, but these people are not just incompetent, they are malicious !
Their service is useless.