What to do?

[Dakota]

Some of the foul lines I have to deal with are pretty foul!

I'd discuss it with the umpire and ask if he is going to call by the lines or call by his judgment of where the line should be. Might be important to know that in the event of a bunt near the line.

Then just play the game based on what he tells you.

I usually use the lines unless they are really bad, then I tell the coaches I'll be using a sight line down the bases, rather than the chalk.