I've read an article that state almost like this:

"Our customers often inquire about the purchase of a power conditioner suitable for a Naim Audio system.
You absolutely do not need one. Most power conditioners reduce musical performance dramatically. Do not If the power is dirty, you can't improve it with a power conditioner without taking away some of the remaining quality and punch."

Is the statement for real?
Are we being 'robbed' by power conditioner manufacturer?