I have been approached too.
My worries are:
1) That users will hate it
2) How well it will work on an information site. I do not have a lot of product names, although there are some pages that refer to product types that should be lucrative
3) Whether it will add spurious links (e.g. take something that has a different meaning in context to refer to what they are advertising). I have a similar problem with adsense.