If you have got different opinions on it and can't find it in thier terms you should contact adsense about it.
If your traffic is generated through traffic exchange sites it's not allowed, You aren't allowed to artificially inflate your traffic, But if you mean a site that offers a traffic exchange service, I don't know.
too bad, google adsense team sent me an email said TE site is not allowed for adsense placement. Any idea what other publisher services i can use that can give equal or better returns compare to adsense ? thanks