5.2 How vs. what

Examples of errors:

(1) How's it called?
(2) It's difficult to say how she looks like.

What is an interrogative pronoun; it substitutes a noun phrase or noun clause in questions, e.g.:

What is that painting called?
It's called "The Little Red Schoolhouse".

How is not, strictly speaking, a pronoun, but a pro-adverbial--a substitute for an unspecified adverbial phrase or clause, e.g.:

How did you come here?
By bus.

It is logical, then, that what rather than how is used in the question What does X look like? since like is a preposition, which requires a noun phrase object, as in

She looks like a wet weekend (i.e. sad).
*She looks like sad.

In combination with stative verbs, how and what...like replace an adjective phrase, e.g.:

How does she look?
She looks fine.
How is it?
It's great.
What does the meat taste like?
It tastes wonderful.
What is your house like?
It's small but comfortable.