I thought, for argument sake, to include some sources;
http://hepatitis.about.com/od/prevention/a/fecaloral.htm
"When disease spreads through the fecal-oral route, it means that contaminated feces from an infected person is somehow ingested by another person."
http://www.drhull.com/EncyMaster/F/fecal-oral.html
"Many diseases of humans are passed via what we euphemistically term, the "fecal-oral route." This is a polite way of saying that infection-laden stool from one person found its way into the mouth of another, with the expected consequence of infection."
I hope that is sufficient in defining "fecal-oral route".
You basically said the same thing as me. It's not the saliva that's infected (with A), but the feces that are transferred to the mouth. "Fecal-Oral" literally means "Fecal [to] Oral". It's no trick statement. It's like looking at crossroads ... Wilson Way/Anderson. It doesn't mean Wilson Way turns into Anderson. It literally means Wilson Way AND Anderson.
Well,I beg to disagree with your understanding of fecal-oral route. Oral means eating or drinking contaminated substance. Fecal means the feces are contaminated and therefore water or food in contact with the feces are contaminated too.
"Fecal-oral" route is a route of transmission of diseases, in which they are passed when pathogens in fecal particles from one host are introduced into the oral cavity of another potential host (my fiance is going through medical school and just covered this topic). As for B, I recall reading a recent article that said "trace amounts" of blood were found in saliva of infected people -- when they had some form of gum disease (bleeding gums).
Hepatitis A is transmitted via the fecal-oral route and person to person contact. So I would certainly not share a cigarette with a Hepatitis A infected person. As for Hepatitis B, the virus has been detected in saliva but whether in sufficient quantity to infect is unknown. As a general principle of good hygiene, I would not share personal items with anyone, let alone a cigarette, a harmful weed.