First of all, I would like to say that it is my own opinion based on my own experience. There can be more or less Internet fraud depending on the country you are from, our language pairs and your profficiency level. Well, in the former Soviet Union there are quite a few people specialising in this shameful business. They like getting professional services for free. I met another person like that just a couple days ago, but thank God I had enough experience already and immediately saw that something was wrong in the way that person communicated with me. He contacted me on one of Russian translation portals, so I wrote to other translators there and asked if he had contacted them, too, and, in case he had, if they got the same test assignment. As soon as we found out that each of us got different pieces of one big project as a test translation, his intentions became clear. This person is now banned on that portal, hopefully for good. But I have quite a few friends who are just thinking to start their career, so I thought it would be helpful for them if I wrote down some of my ideas on how to identify those people and how not to be deceived.
1. Their projects are usually big. At least they say so. And they say that if you do well with a little test piece, you'll have enough work for at least a couple months. Now, there are many decent clients offering big projects and it's okay if you have to do a 150-200 word test in order to win the project. But those who want a free translation from you usually make their test pieces larger (e.g. this person I met a couple days ago suggested me doing 2 standard pages) and it's generally pretty hard to determine what those test pieces are about because they are usually taken from the middle of the text, not from the beginning. In some translation portals it's possible for a client to attach the test piece so all those wishing to take the work could see it. That's the best option, I think.
2. They are usually in a hurry (though not always). They want things done quickly, and the moment you send them the work they disappear. They stop answering you email, the change their id in instant messengers, they may even remove their data from the translation portal where they registered when they needed your services.
3. Watch the time when they contact you. It is always very funny when a person contacts you late in the evening and tells you that he or she is working for a large corporation. Large companies and serious translation agencies have scheduled work hours! And they have weekends! But here you need to consider the time zone of your client, or course. =) Some of my favourite clients from the US write to me late at night or very early in the morning, because our time zones are very different.
4. Note for those working with clients from the former USSR: Please work with new clients only with 30 or 50% advance payment. This is a normal practice here, so please don't feel uncomfortable when asking for it. And if your client is making excuses for not doing it, there's a strong possibility that you won't get paid for your work at all!
5. Most translation portals have a section where translators share their impressions from work with their clients met via this portal (BlueBoard in ProZ, Hall of Fame and Shame on Translatorscafe etc.). Its function is to inform you about the experience of your colleagues and thus can tell you what to expect from this particular client. Please study it carefully before accepting your work assignment.
6. Their messages are usually quite controversial, they don't give you full details of the project and they never show you the full project. For example, this person I met the other day first said that he has a big project of over 70 A4 pages. I answered that I need a more precise quote in characters (it's more common in Russia to count the volume in characters, not in words). And then he got back to me with the number of words. There can be other inconsistencies in their messages. You just need to be alert.
7. IMHO: There are more chances to meet such people when you are just beginning your freelance career and when your prices are lower than those of more experienced colleagues. But gaining experience and raising your rates won't guarantee that you'll never meet them.
And finally, THERE ARE MORE GOOD PEOPLE THAN BAD PEOPLE. Please don't treat your new client as if he or she is planning not to pay you. I get proposals from individual clients who know very little about such specifics of our work as wordcount, average speed of translation, payment methods etc. And it's ok if they don't know something. It's our responsibility to help them.
Hm... I guess that's it for tonight. More ideas and comments from you are welcome =)