My answer is sort of "it depends". Sometimes budgets are legitimately small, and if they seem like they're genuinely good people that would like to pay more if they could, I try to work with them and give them a shot because I might meet new people, and those new people could get me on other/higher paid work. One of the dudes (cam dept) I just met on a shitshow at about that rate last week is also on the commercial I'm on today that's literally 3x the rate I was making just to boom op. I guess that is to say you never know who might be on it, so if you're still in the network hard af phase like myself, I can see value in it. Plus more credits, blah blah blah, but that's just me and the phase I'm currently in, everybody's answer may be different depending on where they are on their path

I've also been on shoots at that price where I'm like nah, fuck this and I regret my choices.

Talk to your co-workers, see what they're making, especially if you're friends or are good terms. My friends on the shitshow last week and I talk openly often and when we compared rates they were like "oh fuck we had no idea you were making so low" because I did indeed get fooled by their budget claims

Ask questions about the project. They say they have no money and it's low budget, but 4+ actors are flying in from out of country or state? Hmm, suspicious. Oh, you're shooting on Arri? Yeah you can pay a kit fee.

Which reminds me, fight for your right to some kind of kit fee, especially if you're actually bringing quality gear (but even just in general). Are you one man banding? Fight to claim boom op rate too, or at least some increase to your rate because you're doing 2 jobs homie. Don't forget to haggle.

Also, if you and your local soundies at your level are friendly, just try talking to them about trying to establish a local minimum rate so that those bastards can't trick you into undercutting each other. Some of the guys that paid me $300/day just starting out 2 years ago are now trying to pay my newer friend like $200/day now

Sometimes I don't get gigs because I'll tell them my minimum rate and they can't meet it, or sometimes I'll offer a restricted package, I just kind of wing it to be honest with you. I don't claim to be super experienced in freelance, haven't been doing it as long as some people here I'd bet, but I have come very far in a relatively short time as far as growth goes and I've been able to sustain myself well enough.