Let's talk about playing the "kid card"

Maybe it's my bitterness talking but I had another co-worker play the kid card the other day when asking me to switch shifts with her and it really annoyed me. I really didn't care about switching shifts because I had no plans or anything but it bothers me that even if I didn't want to switch, I wouldn't be able to say no because she has no one to watch her kid and I would look like a heartless bitch if I acted like I don't care. And honestly, I don't, it's her personal life and I hate she's in the position she's in (going through a messy divorce, etc, etc) but it's not my problem. It doesn't help that this person works in two stores and lives over an hour away from our store and I don't understand why she continues to be in our store when she still has a job at the one close to her home. When we first opened, it was assumed that she was in our store to "help" since all of us were new but here it is, 4 months later, and she's still there at least a few days a week and it doesn't look like it's ever going to stop. But, I digress..

And if someone plays the kid card, how do we know they're being honest? They could just be making up crap about their kid so they can get an extra day off. Are we supposed to assume they're trustworthy since they have a child?

And, sure, I could make up a list of excuses for not being able to switch/take someone's shift but then my guilt will bother me.. stupid conscience.