I highly doubt that watching CSI is going to help criminals hide evidence and get away with crime. I thought that the whole purpose of these shows were to send criminals the message that they won't be able to get away because there is always an evidence of their crime somewhere.
And perhaps real forensic technology is not as advanced as it is presented on the show, but it's still very advanced. It's a very serious profession that requires education in the sciences. How many criminals have the knowledge and means to pass that?
I agree that there is a CSI effect going on. But I don't think we need to worry about what criminals are getting out of the show. They should be getting a good lesson if anything.