Being paid to review a product is different to being paid to endorse it. If a blog was full of glowing reviews and recommendations I would be very skeptical. There are review sites out there that I'm sure get paid or receive freebies to test out, and the manufacturers would just cop it sweet if it got a bad review.

I think it would be easy for people to get caught up in the whole money making side of it.. especially if the money is really needed, and it would change the whole feel of the blog, and possibly sway their 'opinions' of certain products.