Does "cómo es" ever refer to physical attributes?

Question

One time when both I and my Spanish level were younger, I was visiting Guatemala and would often go to a particular restaurant for breakfast where I was always served by the same waitress.  We go to know each other and one day she told me all about her sister who worked nearby. 
 
The next day I wanted to be polite and ask how her sister was, so I asked, in error, "¿Cómo es tu hermana?" Immediately she frowned and walked away and never served me again, with the manager serving me instead. The only explanation that I can think of was that, in using the verb "ser" instead of "estar", I had really asked, "Is your sister hot?"   That is, how is your sister physically? So my question is, does saying "Como es..." ever refer to physical attributes?

Silvia Piriz · Accepted Answer

Hola Marcos R.
In short, “¿Cómo es…?” does not inherently refer to physical attractiveness, nor does it mean “Is she hot?”. Grammatically, cómo es asks about general characteristics: personality, behavior, or overall description (e.g. Es simpática, es alta, es muy trabajadora).
However, in real-life conversation, especially when talking about a person who is not present and not well known, ¿Cómo es tu hermana? can sometimes be interpreted ambiguously. Many native speakers will naturally understand it as “What is she like?” (personality), but others may momentarily interpret it as a request for a general description, which can include physical traits. That ambiguity can feel awkward in certain social contexts.
If your intention was simply to ask how she was doing, the most natural and polite option would have been:

¿Cómo está tu hermana? (How is your sister?)
or

¿Qué tal está tu hermana?

These clearly refer to her current state or well-being, not her characteristics.
I hope that clears it up and sorry your good intentions led to such an uncomfortable moment!
Hasta pronto
Silvia