There are many things to look for when purchasing used power tools. Never spend your money on a used power tool with frayed electrical cords, unless you plan to have these repaired or replaced. You should beware of any power tool that has loose connections that cannot be tightened or secured. This is especially important for drills and saws. Circular saws should have an intact guard for the upper part of the blade, and guards should not be blocked open or otherwise "defeated". Grinders should have a guard on the spindle or the means to attach/replace a missing guard. If there is no way to attach the proper safety devices, don't purchase the power tool. It's also important to ask how long the tool was used before being put on the market. If you know the average lifespan of the tools you plan to buy, this question could save you quite a bit of money.