It is acceptable to pitch to bloggers about your site? As a blogger, how do you view such behavior? As a webmaster, do you do it and if so, what has been the results? What is considered acceptable/unacceptable?
Should you bound your actions by what is acceptable, or should you bound your actions by what is practical and moral? The question I would ask, to phrase your worries more explicitly, is to ask whether that behavior will make things better or worse for you (because if you ask me, there's nothing morally wrong about telling people about your site). If the blogger were to say negative things about your site on his/her blog, in reaction to a politely worded message, people would react as if the blogger were whining, and your site would get free publicity. If the blogger were to say positive things about your site, well that's certainly good. If the blogger were to inform the cabal that you messaged them then they might organize an ignorance campaign. So, do you believe in the blogger cabal? :-)
I don't know that saying negative things is whining. depending on what they are. I did just such a thing the other day, because the site truly sucked. It wasn't whining because I had no real interest in the site, it was just my opinion based on web design, security, and anti-competetiveness. Honestly, the only thing I was whining was that an old friend had forced me to use it.
But if you ask a blogger to blog about you, you can't coerce them, just say, 'thought you might be interested in url' and then hope they say good things. If they don't learn from the bad things they detail and fix them. Then make a comment about how you made the site better.
Making sure you tell them why your site is relevant to their audience would be a good start. For example mention the occasions in the past when they have covered similar products or services.
That will also help them be certain that they aren't being hit by a cut/paste job.
As a blogger, sure, it's totally acceptable. My best advice would be not to blanket every single blog with a form letter. Take the good with the bad in any review and don't whine in comments if they don't like it, just accept it as suggestions for improvement from someone who sees a LOT of sites; probably the same, if not more, as a VC.