It's easy to say that PayPal sucks, but the problem is really not PayPal. I worked in the software end of the credit card business for over five years, mostly on front-end payment processing systems, and have filed a patent claim on an innovation in dispute processing, so this is an area I know quite well.
In the beginning PayPal was really just a simple escrow service for funds. As they started to get a large share of online payments the credit card issuers (who are very powerful, given that 90% of the market of over 1.5 billion credit cards is in the hands of about six banks) began to lobby to bring PayPal under the same regulatory umbrella the issuers have to deal with, namely all the regulations that stem from the Truth in Lending Act and the Fair Credit Reporting Act. As a result of those acts consumers gained a tremendous amount of leverage in credit card transactions. Disputes are approximately a $4 billion a year problem for issuing banks now, and they wanted PayPal to have to deal with the same thing, from a competitive point of view. In response to the costs of this problem issuers have pushed most of the financial responsibility down to the merchant (the same is true for fraud risk, btw).
In a PayPal transaction in which you are the seller, you effectively are the merchant in a card transaction, as far as PayPal is concerned. What this means is that, 90% of the time, you're going to get the shaft in a dispute, just as merchants do on the card side. Most credit card disputes stem from misunderstandings. The _vast_ majority stem from illegible or cryptic merchant descriptions on credit card statements. People see something that bears no relation to the merchant they thought they purchased from, and dispute it. Sometimes the dispute process results in understanding being reached, but more often the merchant just has to eat it. Usually the merchant doesn't even get a chance to argue the point before the money is debited from their account. The money is gone first, and then they have to argue to get it back. So from that perspective you're one up on them.
And then there are people who understand all this and game the system. Your buyer may be one, or may not. It doesn't really matter. There is no way that PayPal could resolve this without pissing off one party or the other. In as much as most of their business is now between professional sellers and consumer buyers, they will allow the law to nudge them in the direction of favoring the buyer, just as the credit card companies do. Anyone using an escrow service to transfer value should understand how they work, and should expect to lose control if a dispute arises. If the 'escrow' service is PayPal or a credit card issuer, and you are the seller, expect to lose.
It's not like there is a better alternative, assuming you can't just drive over to the purchaser's house and shake hands. You're putting the responsibility for signing off on the deal into the hands of an impersonal third party. If _anything_ smells wrong what they are going to do is default to bailing on the whole thing and sending each party their value back. There is really nothing else they can do. If they had to intervene and play Judge Judy to find out where the truth lies (and in fact they do to some extent) - if in other words they had the responsibility of a justice system - then either they would go away or be too expensive, and you'd be back to mailing money orders.