In several years of eBay trading, and many hundreds of transactions, I have learned a couple of things which I would like to share. I hope you find them helpful.

1. Read postings with your brain, not your heart. If the seller is offering up a sow's ear, don't wish for it to be a silk purse. If you're unsure, have someone else - or more than one someone - look at the posting, so that you clearly analyze what it is you are buying.

2. There are people who will cheat you out of $5. "If you're going to steal, steal big" doesn't always pertain on eBay. There are chiselers who will not ship a $3 item, or knowingly send you a counterfeit $10 pen, and they will keep on doing it. They may get caught from time to time, but they keep on keeping on. I know one pen crook who has used at least three different eBay seller names. 

3. Try, as much and as often as you can, to deal with someone with whom you, or someone whose opinion you trust, has had a previous positive transaction. Not always possible, but this is the single biggest caution I would offer: too many people of questionable honesty delight in using eBay to cheat.

4. There are no eBay or PayPal police. If you've been ripped off, chalk it up. There is NO ONE on the other end to help you.

5. I have decided that, when I encounter a new seller, I am going to ask about him/her/them wherever I can BEFORE I do business with them. If I get no answers, no matter how much I want the item, I have resolved not to buy it.

6. The eBay rules say that the seller should post feedback first, generally as to timeliness of payment. If you are they buyer, DO NOT EVER post feedback before the seller does. If they don't, you don't. He who blinks first often loses, as neutral or negative feedback left will cause you to get flamed, even if you've played by the book.

Don't be paranoid, but do be cautious. Your fellow man is too often ignorant of some very basic beliefs.