What's your experience scraping WP blogs and commenting manually

I am trying to comment manually to the high PR sites, but they are all not letting me do it. Some say "bye by spambot", others just seems to post and nothing shows up, I guess waiting for moderation. What is your experience with manual commenting?

Assuming they have recent comments to show that comments are being approved, it can get you some decent backlinks.

I would blast the high PR sites to see what sticks automatically first then go back and manually comment on pages that have recent comments.

The approval rate for WP blog continue to decrease as more and more web-owners simply don't even approve the comments any more.

The comment really need to be specific to the topic and contribute to the page...