I recently requested and reviewed a lingerie item for free, but only 1 Eden sponsored review is allowed for lingerie which was my understanding as mentioned by others, and you can still request for a buyout review.
When you do the product search there is a filter option so that you can look for products that don't already have reviews. If there are at least 3 Eden sponsored reviews that are good and cover the spectrum, they have the right to deny the product. That does not preclude an administrator assigning something to you though if they have a reason for needing more reviews. I have had lingerie requests and some other product requests denied before, but others approved. It really depends on what I have mentioned. I always look for products that don't have reviews or have a maximum of 2.