Since Am writing this article because I come across the doubt, are Websyndic and Hitleap ad sense safe. The answer here is...
Since Adsense serves top advertiser partners, they mainly depend on good traffic quality and content. Ad sense earnings are based on RPM but not CPM, their CPM depends on traffic quality, using websyndic is not bad for ad sense since they pay very low CPM rates for such sources called external traffic sources, whereas htileap may considered as good traffic source but not excellent. if your website have at least 500 decent page views from Google or any other search engines you need not worry about them.
Abcvisiteurs is also little adsense safe
Here are the small things you have to remember :
hitleap ( 88% score -- Adsense safe )
Websyndic ( 65 % score --- Adsense Safe )
Abcvisiteurs ( 65 % score ---- Adsense Safe )
Feeling surf ( 32 % may be risk ---- I may warn you not to use ..... )
Other surfs ( 10% -- high risk for Adsense )
NOTE : we are not sure about the article, since we have got thousands of positive review on the top autosurf.