How to separate mainsteam and adult?
 

I want to sell some sites, some of them adult some not. If I put them on one page for sale, on a separate domain,will it hurt my mainstream sites (they have adsense and some for kids) that they are on the same page with adult links? I mean what is the level I have to separate the two? I mean I know I can not link them together but how about these issues?

this way you will get an adult link to your non-adult sites that is not good. The domain linking to adult site can be considered mature only for google. So don't put both links to adult and family friendly sites on 1 page

You will harm your websites. The search engines will not show your main stream sites for main stream keywords.

thanks for the info. i was actually thinking about making links. but now i see must keep it separate.

Make it on separate domains. It would be much easier.

mixing one with the other is bad business, man. keep them separate.

use nofollow tags

This.
And never link to your adult page from your mainstream page.

+ noindex in meta...
+ some simple of user verification like 2 + 3 = ___ before loading the page and it should do the trick...

Like other have said, separting them will help, you could also list the non adult site at 3rd party domain/site selling site such as Flippa