I don't think that is the issue. The issue is a publication saying, "Hey, if you take out an ad, we'll definitely review your CD! But if you don't, there's no guarantees." That's shady, imo. Do you really think the publication will print a bad review of the CD if they person paid $1500 for an ad? Hell no because if they did, the band wouldn't even bother with the magazine when their next CD came out and they'd lose that potential ad revenue.
And sure, it happens everywhere. Doesn't make it ethical.