After that, Genie explains that from then on, only valid wishes will be accepted and makes a big deal about it.
"Valid" is not quite right. Aladdin does trick the Genie into freeing him from the Cave of Wonders without using a wish. However, when Aladdin points this out, the Genie insists Aladdin cannot have any more free wishes:
GENIE: (Still as stewardess) Thank you for choosing Magic
Carpet for all your travel needs. Don't stand
until the rug has come to a complete stop. Thank you. Good bye, good bye! Thank you!
Good bye! (Back to normal) Well, now. How about
that, Mr. doubting mustafa?
ALADDIN: Oh, you sure showed me. Now about my three wishes-
GENIE: Dost mine ears deceive me? Three? You are down by
ALADDIN: Ah, no--I never actually wished to get out of the
cave. You did that on your own.
(GENIE thinks for a second, then his jaw drops. He turns into a
GENIE: Well, don't I feel just sheepish? All right, you
baaaaad boy, but no more freebies.
ALADDIN: Fair deal. So, three wishes. I want them to be
Aladdin transcript, emphasis mine
He then references this agreement when saving him from drowning:
GENIE: Never fails. Get in the bath and there's a rub at
the lamp. (Squeaks the duck) Hello. (Sees
unconscious ALADDIN) Al? Al! Kid, snap out of it!
You can't cheat on this one! I can't help you
unless you make a wish. You have to say "Genie I
want you to save my life." Got it? Okay. C'mon
Aladdin!! (He grabs ALADDIN by the shoulders and
shakes him. His head goes up, then falls.) I'll
take that as a yes.
So under the terms of their agreement that Aladdin would not get anymore "freebies," being saved from drowning consumes a wish. In fact, we might argue that he cheated the agreement in Aladdin's favor, since Aladdin didn't technically make an explicit wish to be saved.
This means that Genie did not trick Aladdin in any way. Aladdin's three wishes were used up.