it could be interpreted as dishonest in a number of ways... since the blog post and/or review would no longer be an unbiased review... but rather there was now a financial transaction and thus introducing motive for a more positive review.

it now is a "sponsored" blog post instead of an impartial review.

Couldn't you just build them a beta build? It seems like a no-brainer.

i suppose, but there would be parts that would probably "break" and thus creating a false or "incomplete" experience.

you're right though, there are some other possibilities, i'm sure.