Does posts with labels like "sponsored post" (e.g. posts from payperpost) really decrease PR? I heard that Google doesn't approve of those kinds of posts...
I have heard this also, but I have a PR4 blog with a lot of paid posts and it has not changed...I will however be writing less of them just in case...
Google doesn't approve of them. But it's your blog and not Google's - they'd do well to remember that. They could penalise you in the SERPs if someone reported your site and it was overly spammy. If you're only doing the occasional sponsored post (like 1 post in every 5) then I think you're pretty safe.
i got my PR from 4 to 0 and now i take it more easy and got it back to PR2 so yes they do kick you down to take sponsor post
yes.. because it is against google TOS. google doesn't allow buying and selling of PR and paid post is a way of buying and selling PR. but if you don't want to be detected by google, don't use payperpost. instead, use smorty,sponsoredreviews, or reviewme.
I think the ratio of 1 sponsored post for every 3 non-sponsored posts should be OK. I would not bother with PayPerPost, they are becoming really bitchy about what other advertising avenues you can have on YOUR blog. I have Adsense, Adbite, Kontera & Linkworth and apparently these are not allowed on MY blog! Here is a pretty big list. http://ineeddiscipline.com/2008/06/09/blog-review-networks/
I have had five reviews declined because they objected to me having Adsense & Adbrite banners in the header of the blog which appears on every page.
If your posting will contain some natural links along with the paid links then you can get yoruself on safe side . For example links from wiki , google , about and blah blah ..
My cousin have a blog. he used SponsoredReviews in his blog. His blog had PR4 but now his blog's PR has been removed and also kicked from Google Search Engine too.