To answer your question Lal, in part: Tollers was perhaps of an era, or certainly from the background, where a drink was fun, and a few could be very fun, but people, homely respectable people much like Hobbits (even the younger ones), did not feel the contemporary urge to drink as much as possible in order to become paralysingly inebriated, to the point where a kebab seems like a good idea.
One imagines that the beer they are drinking is also fairly natural wholesome stuff, with not much in common with the watery additive-syrups posing as lagers today. A couple of beers from natural ingredients on a full stomach over a few hours of chat, is unlikely to give an adult male a headache.
Add to that that the small folk always drank on exceptionally full stomachs and had plenty of rest and a proper amount of sleep, as well as having healthy outdoor lives much of the time, and you begin to see how they managed to stay pretty sharp.
To be honest, if I had little to do all day but to wake late, rise later and go for walks and plan dinner, I imagine I would become somewhat inured to the 'morning after'.
