It seems to me that providing monetary incentives (or incentives with a clear monetary value, like a cup of coffee in a specific restaurant) for submitting revi

It seems to me that providing monetary incentives (or incentives with a clear monetary value, like a cup of coffee in a specific restaurant) for submitting reviews would attract the wrong sort of crowd. An entire new class of reviewers would start using these services. One example would be people who submit a review of a place just before they arrive to get their free coffee. A more worrying case would be users who write a script to generate and submit reviews automatically. Generating text that _looks_ like a review is not difficult and, unlike spam mail, it wouldn't require plugging a product (which is what gives spam its distinct spammy flavour :)) or generating millions per day. In practice, it would be very difficult to filter that sort of thing out and there would be so much noise that the value of the site to real users would plummet.