An interrogative phrase *How* replaces the preposition phrase including any prepositions:

 - **How** [does it look <s>**like something**</s>]?

An interrogative phrase with *What* just replaces a noun phrase:

 - **What** [does it look like <s>**something**</s>]?

So, in short, the Original Poster's intuitions are correct. If we try to use *How* but not delete the preposition, the sentence will be ungrammatical:

 - *How does it look like? (ungrammatical - *like* should be deleted)