It should go without saying, but for the record: TUAW isn't involved in this practice, and never has been. We will use promo codes for reviews rather than buying the apps directly, but a promo code doesn't guarantee a review and it definitely doesn't influence our stated opinions on the products we cover. Informally, our editorial team gives a thumbs up to the OATS standard, although TUAW hasn't officially joined the sites promoting the 'code of conduct' for app reviews.
Nevertheless, this is an interesting issue. My main question actually revolves around whether or not this practice actually "works" for the developer -- do devs who pay the $25, or whatever these "Reviews R Us" sites are charging, actually see returns in their product's sales or downloads?
We know (based on detailed reports from multiple developers) that apps we review or mention here often see boosts in sales and performance in the App Store. We presume that's due in part to the fact that we don't do "payola" -- our readers trust us to post about worthwhile apps, and thus give their business to the ones we cite. Do these App Store review sites that are charging for their services see the same effect? Are these developers that are pouring $25 into "Joe's Review Shack" for an "expedited review" getting their money back in sales and/or downloads?
If they are, something is wrong -- either there's just not enough trusted outlets for apps out there, or even the App Store just isn't big enough for its own demand. If people are downloading and buying apps just because they see them mentioned anywhere (even on a site that they can't trust), then maybe there just aren't enough quality apps to go around. Payola doesn't work in the case of film reviews, because there are enough trusted reviewers and enough good films that you have the option to pick and choose the ones you like, paying attention to reviewers you agree with. But it does work in the case of old-school radio, where you only had one station to choose from, and you listened to (and bought) whatever songs they played.
Of course the first question is whether these sites work or not. If the $25 invested in one of these payola sites actually pays off for an app that clearly doesn't deserve it, then there might be a bigger issue with the App Store ecosystem as a whole.