I'm a guilty party, that was trained using bad phraseology. After getting my instrument, I finally realized why controllers always made me read back a lot. So I started to read the ICAO guide for phraseology, and I actually get compliments on correct read-backs. However, I am still fighting bad habits and trying to switch over to "negative contact".
I have noticed about 70% of pilots and 20% of controllers use incorrect phraseology. Sometimes it drives me nuts when the controller does it. The pilots outnumber the controllers though, and the professionalism is down. I would actually recommend for everyone to read the ICAO standardized phraseology guide. Eventually, we will all have to switch over anyway. Someday...