Meal time...

[Bogertophis]

It happens sometimes and doesn't seem to be a problem, I watched one of mine trying to eat a rat for an hour and a half she finally got it, just takes time. One thing that I've found that helps is the way I hold rats/ mice. I hold them just behind the head (think of how a mother cat holds a kitten) with the face looking forward toward the snake. That way they almost always hit the head first and start eating there.

I know, I've seen one struggle for a LONG time also...they don't give up easily, that's for sure.
I feed most of my snakes off my tongs, & I have one that, no matter which end I offer first, he wants the OTHER end!?

... Don't know if this theory holds any weight, but I remember reading somewhere that they could possibly get confused which end is which if the rats are frozen in a big bag all together, and one rat's head is stuck right up against another rats rear end, causing some of the oral scent of one rat to be transferred to the rear end of the other.

I also don't think this explains it: I've always raised my own rodents & offer fresh-killed just as often as f/t...makes no difference.