I don't think the number of a noun in a language affects my conception of the thing in any way.
Spanish uses a singular,
el bigote, but I can easily see it conceived as divisible in two symmetric parts (in most styles). Hearing a non-native speaker say
los bigotes when talking about a single person would be weird because that's not the Spanish linguistic
convention, but it wouldn't be weird in the sense that the plural view is hard to understand. (Also note that
los bigotes does exist when talking about a cat.)
For another example, whereas Spanish uses a plural noun for the game of
las damas 'checkers (US), draughts (UK)', both English and more obviously German (
die Dame) use singular nouns (
checkers is boring, note the singular "is"). Do I conceive of the game as multiple things because the noun is plural in Spanish? No. In fact, I can perfectly even say
las damas es un juego aburrido 'checkers is a boring game', even if otherwise I'd use a plural adjective when modifying the noun more directly:
las damas son aburridas 'checkers is boring'.
Similarly, in Mandarin they don't count "languages" with a normal counting classifier particle, but rather talk about "types of language". In the same way you talk about 三種書架 sān zhǒng shūjià 'three types of bookshelves', you're supposed to say 三種語言 sān zhǒng yǔyán 'three languages' (literally "three types of language"). If you want to talk about three bookshelves without caring about the type (maybe they're of the same type, maybe not), you say 三個書架 sān ge shūjià, but you cannot say *sān ge yǔyán for 'three languages' (unless you want to sound weird like the Spanish learner talking about his dad's "
bigotes"). Does this mean that the European concept of individual languages is alien to Mandarin speakers, who can only conceive of a single nebulous "language" abstraction? No, most Mandarin speakers can perfectly list a number of different languages (English, French, Japanese...) and insist that they're different (while, of course, some of them also insist that Mandarin/Cantonese/Hakka/etc. are geographic variations of the "same" Chinese language).
By the way, I asked a native French speaker from Paris, and he said
la moustache is what you normally say.
Les moustaches is typically used for cats, and if you use it for a person you sound like deliberately going for an old-fashioned/archaic sound. Otherwise,
les moustaches when applied to a single person mostly just exists in highly idiomatic contexts, notably the joking/absurd saying
par les moustaches du pape ! (literally "by the moustaches of the Pope!", compare English "
by Satan's whiskers").
.
