[chrispenycate]

The story obviously wasn't good enough; otherwise he wouldn't even have noticed. And, despite not having been born in august, I am amoung the world's worst at being distracted by inconsistancies in detail (oh, you'd noticed)(in french we say "enculer les mouches", which is extremely impolite, but fairly accurate) No-one can be certain of historical details- but you can't be certain of what's happening now, only to a certain percentage. Pottery shards and glass splinters last more or less for ever, so, unless they were recycling the glass, one gets a reasonably accurate (not perfectly certain) idea of the ditribution of the two. Metal vessels are far more likely to be melted down for reuse, meaning that the estimates for metal drinking vessels is likely to be less precise. Biodegradables (if they were using waxed papyrus cups we'd never know) depend on conditions, meaning that estimating the distribution of wooden mugs (or leather jacks) is guesswork- that they existed is certain, whether they existed outside the regions where, by desert or peat bog or glacier, they were preserved will remain uncertain.
Still, the important point is whether the detail shocks you enough that you drop out of the story, whether or not you put the book down and start doing research to find out if you were right. Some of us are simply more sensitive to these problems (and I'm someone who can keep reading while the plane I'm in flies through a thunderstorm, feeling quite agrieved when the light flickers) and I suppose this is one of the factors that divides people on favorite books.
But one thing is certain- the earlier in the story the problem arrives, the less likely a reader is to gloss over it and continue in the thread.