Appearance or appearances: Ambiguity in meaning?

People care way too much about their appearance/ appearances?

Google provides much more evidence for the singular but I have learnt not to trust it. In a formal essay I would opt for the plural since people do not share the one appearance, but I would like some clarification with this if possible.

The older question "On their back" or "on their backs"? is different from mine because the plural form has no other meaning. Whereas the word appearances, the plural can mean physical appearances as it can multiple looks. Furthermore, it would be incorrect to use the sentence "people love their life" as it implies they share one. Yet lives has two meanings as well. Why is the plural correct in that context? So I was hoping for an explanation on this.

Solution 1:

'People care way too much about their appearance' usually means that people, in general, are over-concerned with the way they look to others. Each person has only one way that they look, hence the use of the singular.

'People care way too much about their appearances' might mean that people, in general, are over-concerned with their performances [in movies, on stage, on TV and so on]. Each person could have a number of such 'appearances', hence the use of the plural.

In both cases the use of the word 'their' indicates non-gender-specific singular possession, and not possession by a group.

Solution 2:

Ngram Viewer agrees with Google and says by their appearance (blue line) is more commonly used than its plural equivalent by their appearances (red line).

There is also the expression "judging someone by their appearance" which is derived from the Biblical proverb “Do not judge by appearances, but judge with right judgment.”; John 7:24, and its more recent secular version "don't judge a book by its cover". Note however that the plural form is used in the older proverb, which hints that appearance, meaning visual aspect, is also countable. And to muddy the waters further we also say: “appearances can be deceiving”. Perhaps when the term “appearance” is preceded by a possessive determiner such as our or their the singular is preferred. E.g., We spend far too much worrying about our appearance

Ngram Viewer

Examples

• Other studies also support the notion that people are judged by their appearance
• Even though it has been found that good-looking people earn 12% more than their plain colleagues, with the difference in pay being more acute for men than women,12 women are certainly judged by their appearance.
• It is inevitable that products will be initially judged by their appearance and, if no other information is offered, consumers will deduce good taste and good internal quality from good, visible characteristics
• Infected fish can easily be distinguished by their appearance; the outside of the body turns white and the fish appear larger than healthy

In the above examples appearance refers to the way in which something or someone outwardly presents itself to view. If you substitute (physical) appearance with beauty, attractiveness or aspect, the abstract nouns remain singular.