i would not use Paypal for LABOR payments, its too easy to lose money. Use GOOGLE CHECKOUT, much easier and there is less chance if a chargeback happening.
Heres the problem, PAYPAL plays mediator. They dont know the difference between you and the buyer, and who ripped who off. They will 99% of the time SIDE WITH THE BUYER. The buyers KNOW this. All it takes is a buyer to say that you didnt "perform a service you said you did" and your up shits creek because even if you CAN prove it, paypal isnt in any position to believe you.
If someone just send you money and it isnt designated as "labor" you are fucked instantly. you are at risk ANYONE can do a "dispute" and paypal will require a tracking number from you. If you tell them it was labor, they will reverse the payment and send the money back to the "buyer" and send you acct negative if the money is gone.
DONT DO IT ive been through it all.