Learn Italian: Ho visto il cameriere che puliva il bancone. - I saw the waiter cleaning the counter.

This sentence uses a pseudo-relative clause, which is the standard Italian way to express seeing or hearing someone doing an ongoing action. You use a perception verb like Ho visto, the object il cameriere, the word che, and then the imperfect tense puliva. The imperfect is required because it highlights that the cleaning was an ongoing, unfinished action at the exact moment you saw it.

Could I use the infinitive here and say Ho visto il cameriere pulire il bancone?

Yes, absolutely. With verbs of perception, using the infinitive (pulire) is another correct way to translate this. The che + imperfect structure just puts a bit more focus on the action being in progress, while the infinitive is slightly more neutral, but they are generally interchangeable in everyday speech.

What would happen if I actually used the gerund and said Ho visto il cameriere pulendo il bancone?

That would completely change the meaning! In Italian, a gerund like pulendo almost always connects back to the subject of the main verb. So that sentence would mean "I saw the waiter while I was cleaning the counter." To show that the waiter was the one doing the cleaning, you must use the che + imperfect structure or the infinitive.

Why does the word for counter, bancone, end in -one?