Tell me about your product or service and why you think its super cool. If I think that product would be of interest to me (and my readers) odds are high that I'll agree to give it a go. But I also have the right to say “no thanks.”
I won’t object to compensation for writing about a product or service, but compensation doesn’t guarantee you a glowing review. My reviews are based on my observations and experience. If I love, I write about it. If I don’t. Well, I write about that too. If I am compensated to write the post, I will certainly include that information in the post.
Oh yeah and any press releases asking me to promote a product without an offer to try the product? Get trashed.