tell hunting

[dark_horse]

this situation has come up with me a few times now:

i bet, opponent folds, i muck. opponent asks me a question about my hand. i answer whatever i feel like saying (true or untrue), and then i say "what difference does it make? you'll never know if i was telling you the truth." and then i get this. "it doesn't matter, i just wanted to see how you'd respond."

what could my opponent gain from seeing "how i respond" if he doesn't know if i'm telling the truth? gauge how i look when i said that vs when i've said something that's obviously truthful? that's the only thing i can think of. that, or he's just saving face because he really has no point.