And that speaks volumes for Tape Op, as _I_ certainly can't pay 'em off for good press!
I've written a couple of gear reviews for Tape Op (including one in the current issue). I will say definitively that payola-for-review doesn't happen-- which is the best thing going for that magazine. The writing isn't always the best, and the reviews aren't always the most informative (sometimes there is bad or incomplete information, or leaps of logic). Writers don't get paid all that much for gear reviews.
But basically, the writers get to review what they like, and it's not that hard to be able to write reviews for them (one of the reasons I did is that I felt it was a better action than merely complaining about the standard not being higher-- get involved, raise the bar).
After a review is written, someone on the magazine's staff will usually reach out to the maker or manufacturer and see if they want to purchase advertising in the issue with the review. If they decide to do so, they'll make every effort to place the ad on the same page as the review, or on the facing page. But I've never heard of them pulling a review because someone declined to buy ad space, or choosing which reviews get published based on any economic kickback.
I don't read much in the way of recording magazines these days, but the subscription is free so it keeps coming. Not everyone is interested in the DIY/indie/low budget slant (truth be told, I'm not really, anymore) but the way it's run at least seems to have integrity, which is a positive.