First let me be clear to say I don't speak for the Daily Post on this, just my personal opinion:
I do agree taste test's in the DP can be a bit too positive, I think a discerning critic is what's best for all, especially as some establishments could probably do with some constructive criticism.
It's important to remember the reviews are not anonymous so complete slayings are discouraged - you never know if a business owner might take it the wrong way. I remember a taste test I did for a previous paper while on work ex which was overly acerbic and I was told to tone it down. Chances are if you hint at inadequacies, they'll be picked up on by the reader.
I can assure you though no payment is involved for a taste test (or at least, I'm yet to receive one).
Oh and I forgot I did a taste test for The King's Head in Llandudno. Wasn't much a fan of that one (good beer and decent food, bad service).
Edit: To add, I personally prefer to go in unannounced on a review and have them only find out when our toggy goes to take a shot of the establishment, I know others might think differently. Sometimes they do know ahead of time due to stories I've done on the business (Departure Lounge, Paysanne) and, if so, I like to include that in the review - in the interests of full disclosure.