Most stations spend lots of time touting themselves. To be fair, however, you have to keep in mind that the FCC requires them to identify themselves at regular intervals and, if you're going to identify yourself, you may was well through in a plug. If you're going to have to say "This WXYZ in Cleveland", it's takes little more to say "This is fabulous WXYZ, Cleveland's premier radio station", especially since all they do nowadays is turn on the tape, they don't even say it live anymore.
They also spend a lot of time advertising for advertisers, explaining to them how effective their advertisements are, but, what they hey, it's the business they're in. If it keeps the music free, so be it.
We have one station here that frequently interrupts its 'commercial free song sets' to let us know that they are playing a 'commercial free song set'.
I'm not sure how much ZZ Top gets played, however, since I don't listen to 'pop' or 'classic rock' stations any more.
Quod scripsi, scripsi.