I always heard it was, from photographers doing State and Local campaigns.
"We might not get paid. If they lose, we will NEVER get paid."
If I was her vendor, I’d send the following:
“Dear Hillary: You are indebted to my production company for the sum of $xxxxxx.xx. I’d like this debt paid by this coming Friday. Should you choose not to pay, I plan to file suit in state court in Indiana, have myself appointed as process server and personally serve you with the complaint at your first “town hall” meeting in front of TV coverage cameras. I will have my 15 minutes of fame, and you, well . . . , you get the picture.”
My company requires ALL politicians to pre-pay. And we sell lots of political stuff.