will adsense will allow PLR content site? No unique content? What about content from popular forum post? I am not asking about search engine penalty for duplicate content.. I am asking if adsense will allow such site..
Yes the adsense will allow such a site. Adsense does not allow stolen or illegal content and PLR is neither. You would not get any traffic to such a site though, so I do not see much reason for making it. Keep in mind that adsense arbitrage is dangerous these days and frequently result in an account termination.
There have always been webmasters using PLR content to build their website but I would rather prefer unique contents instead. If you are using source of info from forum posts, it would be better if you just rewrite it rather than direct copying.
I think the best way to do it to use the PLR content to supplement your unique content and help you rank better in the SERPs. Note that the Adsense Program Policies require publishers to adhere to their Webmaster Quality Guidelines. Part of those guidelines: