If one of website against terms and conditions, google ban full adsense account or only website that against Google terms and conditions. I like to know Google send warnings before ban for content issue of website.
i have seen them ban entire accounts and only websites. Generally you will get a warning, but not always. It is best to read the terms and conditions and be careful not to break them.
some times they suspend site and adds don't show on the banned site but you can get it reviewed and working again. but if you keep getting warnings they will definitely suspend.
for me they disabled ad serving on my 2 sites, they did not ban my whole account, but i think i m lucky, i heard they banned whole account some times.
If google are going to ban your account, they generally do so with no warning whatsoever. You can appeal but you have more chance of pushing a sausage up Everest than having your account reinstated. Be very careful for Google is a wrathful god!
if minor compliant or content related issue with the site, then you will get an email asking you to remove the questionable content from your site. if spammy content or pirated content are used on the site intentionally, then Google can ban the entire account.
If any fake id create by user google also reject their adsense request .They varify user by calls also .