When two people are talking at a party and the one listening really isn't. Instead they'll look around to see if there's someone else they would rather be talking to. Consequently, even though they're nodding their head and smiling, they're not paying any attention to you.
The same could apply to evening/weekend invitations. A person will accept an invite and then cancel because they received another/better offer to go somewhere else.
"Dude, when I invited her to go away with me for the weekend. she said she would love to. Then an hour later she cancelled saying that there was a party she wanted to stay in town for. She was totally better dealing me."