Scams that target small business can come in a number of forms—from bills for advertising or directory listings that you never ordered, dodgy office supply offers, to false claims of government requirements needing you to send money.
The best defence you have is to make your business as protected as possible—by limiting how many people have authority to buy or order anything, keeping written records of all orders and purchases and by making sure you only deal with people you know and trust.
The Small Business Scams fact sheet provides more information and tips about common small business scams.
Don't let tactics like bullying, negotiations for a lower price or charges for unordered/unused goods affect your decision.
Do not rely on information given to you by whoever offers you a particular product or service—always seek independent advice if the product or service will involve a significant amount of money or other commitment.