It is hard to document rumors. I would ask (when they say that) to show you where you can read it. Then you can make a decision to believe it or not. I mean, if that's what they say at AdSense, then it must be true.

Well, I would say it's partly true not because there is any such rule on the age of the blog but because age is just a by-product of other considerations such as content quality and traffic. People usually get confused between 'cause and effect' and put such assertions. Adsense approval require you to have some quality content on your blog. It is also helpful if you have some organic traffic on it. In a nutshell, it should be a live blog with quality content and traffic where advertisers want to advertise their products and services. All this content and traffic building takes time (easily 3-6 months). So, saying that adsense do not approve new blogs will be a fallacy - it doesn't approve blogs with no content and no traffic which is mostly true in case of new blogs. So, before applying for adsense, get your blog to a stage where it has some quality content and some traffic - age of your blog will not be an issue. Also, go through a very detailed post about adsense approval here - [webmasterworld.com...]

It is a rumor and partially true. Every newbie blogger is inspired by successful bloggers who earn huge income from Adsense. Many folks start their blogs for the sake of making money from Adsense instead of creating quality content. They actually forget what Google expects from them. Bloggers should strictly adhere to AdSense policies, otherwise, it will be hard to get approved. In my case, I followed the guidelines provided by Adsense and I got approval for my blog which was 2 months old at that time. Adsense team will manually review a blog and will decide whether to approve or not. A blog must convince the AdSense team to get the reply from them as "Your website has been approved to show AdSense ads".