Usual dialogue/s

[Molly]

Which dialogue/s would native-speakers more commonly expect to hear?

A: What a beautiful dress!
B: Thank you. I’m glad you like it.

A: That’s a cute dress you’re wearing.
B: Really? This old rag? I got it at the Salvation Army for $2.00!

A: That’s a cute dress you’re wearing.
B: You’re the third person today who’s complimented me on it. I must have done something right!

[Prezbucky]

All three are equally likely, IMO.

The first would be most likely among two people in a formal relationship... like a worker talking to her boss.

The second might be heard among old friends. "Rag" is not youthful slang. Here I'm thinking the convo is between two old women who maybe were hippies in the late 1960s.

The third is less age-specific and is the least telling of the demographics/social situation of the characters.

But really, despite the small differences, I wouldn't be surprised to hear any of those in everyday speech -- none of them are head-turners.
_________________
Billie Jean is not my lover. Hee.

[Molly]

[Prezbucky]

I would not be surprised to hear any of them -- they're all fine.

There are myriad ways to create this conversation:

Yo, that dress is hot. Tssssss.
Yeah, player, recognize. Thanks.

What a gorgeous dress you're wearing, sweetheart!
Like totally thanks.

When God first pictured the dress, He had yours in mind.
Thou art kind, and I thank thee.

hehe

You're hot in that dress, girlfriend!
Thanks, girlfriend, it was free. Don't tell the cops.
_________________
Billie Jean is not my lover. Hee.

[Molly]

I can't keep silence over that dress you're wearing.