Very unlikely...Unless you fill everything with adlinks. It should not appear spammy.Both for visitors or search engines.
Don't go with something like InfoLinks, don't have more than 5 or 6 banners per page, don't fill the page with I'M MAKING $300 PER DAY ONLINE. LET ME SHOW YOU HOW YOU CAN TOO!, don't force people to read ads before seeing content, etc etc.
You want ads on the top and on the right side of your blog. That's what Google recommends. More effective for clicks.
In more simple way always give your blog content first priority make sure it is easily readable to readers as well as to search engine bots.Don't mix your ads in your post content.Always maintain your blog standard.
ya you can sell contextual link but dont add so many links if you add so many links then it well effect your PR
unique visitors/page views is what is attractive to advertisers, not pagerank (if you are not just selling PR).