Reply by Tim McCulloch
We have several clients that get production on credit. We bill “Net 10.” Most of the time our check is there. We get a 50 percent deposit when the contract is signed, and (depending of the client) get the balance upon arrival, or before the show.
If a client doesn’t have the money at the agreed upon time, I won’t do the show. The advice in this thread about legal action and bad press apply. You have to attempt to collect the debt before you can sue – how long and how hard depend on your local laws.
Be very careful about what you say to others. Don’t “characterize” a non-paying client. Calling them a ‘no-good, child molesting, non-paying…” will get you sued. Stick to the facts, i.e., “he is 30 days past due” or “she didn’t have the money at the end of the gig as promised, and I’m still waiting.”
As for contract language, you can ask for almost anything. Whether or not its enforceable depends on where you live or work or the contractually stipulated jurisdiction. (“This contract is made under the laws of the state of ________, and in the event of litigation it is agreed that the court of competent jurisdiction is the ______ court of ________.”)
If you do sue, remember that judgment is NOT collection, and you could be tied up for years chasing money that loses value every month after judgment.
As for the mob hit – dead clients can’t pay. And somebody would have to owe you huge amounts of money to get you indebted (even if you paid cash) to the mob for a broken leg or arm to “convince” your client to pay up. It sounds like fun, but you don’t wanna go there. Trust me. 
Our rental contract specifies that equipment be returned in the condition it was given to the client. We test (in front of the client) every major piece of gear in their package; amps, speakers, mics. Most of our “carry-out” rentals are powered mixers, speakers on sticks, etc. so its pretty fast.
We have them initial a checklist indicating working status and physical condition (just like renting a truck from Ryder). WE test each with the client when it comes back.
Discrepancies are noted on their contract and arrangements for additional monies are then made. Security deposits depend on our comfort factor with that client… we’re going to a credit card based system where we will get an “authorization” for up to the total value of the equipment if we think we might need it. If the card won’t go through, we tell the client they can’t have the gear.
Our contracts state that all rentals are conditional upon credit approval. Some existing clients are not required to do this. You are the person granting approval, so as long as you don’t withhold that approval based on race, religion, national origin, etc. you should be OK.
The info on the workers liability a while back sure helped. But what if your friends help you? Can you be held responsible if they get hurt?
Your friends are employees unless it is explicitly agreed they are volunteers, which makes them free to come and go as they please, even not show up. If you require them to do anything, they become employees.