did <verb> and <verb>

While reading A Dance with Dragons by George R. R. Martin, I came across the following line which seemed odd to me. (Note, English is only my third language so "seemed odd to me" is about as meaningless as it gets)

[...], even if he did look like a monstrous yellow slug and smell of piss.

The smell part is what seems off to me, though I realize there's an assumed repetition of he did. I guess I just find it sounding odd.

Is the used phrasing correct? Is it also correct to use the following line?

[...], even if he did look like a monstrous yellow slug and smelled of piss.

Which way is most common in English?

Both are possible. In the original, as you say, he did is understood. You could also write:

... if he did look like a monstrous yellow slug and did smell of piss.

In your example, only the subject he is understood and so you would still need to mark the verb as past. Personally, I don't like the combining of the two different forms of the past tense with and.

For example, I don't like:

He did go home and ate.

This is essentially what your second sentence is.

A better comparison would be:

He is walking and talking on his phone.

He is walking and is talking on his phone.

To me, both are equally correct, but the first is much more common in English. The repetition of the auxiliary verb is (or any other auxiliary for that matter) is more common when there is a large separation between the two verbs. There is no simple rule as to which is the most common.

Sure, it's fine. This is a case of ordinary Conjunction Reduction from

• even if he did look like a monstrous yellow slug and even if he did smell of piss.

Emphatic do, like all usages of do, must be followed by an infinitive, not a tensed verb, at least if Conjunction Reduction has applied. But clearly something must have applied to delete the subject of smell, as well as the even if introducing the smell clause.

In addition, this sentence has parallel uses of two Flip Sensory verbs, look and smell. Flip Sensory verbs have subjects referring to the source of a sense experience, rather than to its experiencer, like see, hear, listen, etc. do. This is a rather nice parallel structure, something which always makes a sentence slide down easier. And it's another reason why they ought to be inflected alike: to maintain the conjoined Verb Phrase structure.

I would have used "smelled" myself, but there's nothing wrong with the sentence as it stands. Martin writes in an affected style, characterized by some as "Wardour Street English," of course; still, consider this clause:

Even if he did lie, cheat and steal ...

All present-tense verbs, and no problem anywhere. It's the disproportionate size of the first verb's complement compared to the second that makes the sentence feel funny.