Got a domain name idea? Don't try it in the address bar!

Inevitably, there's an industry based on stealing domain name ideas then reselling them back to the creator at a premium.

It's hard to know how big a problem this really is, but this article mentions the selling of "Non-eXisten Domain" (NXC) data:

Stealing domain name research

... It is such a strong urge to type the domain name into the address bar and see what website comes up. Most users think perhaps there is already a company using the name and this will be a quick end to the question. Wrong! This is the most dangerous thing to do. Internet Service Providers (ISP) sell NXD data. You may be asking yourself “What is NXD data and how does that effect my domain research?” Non-eXistent Domain (NXD) Data is a response the DNS system tells the asking computer if resolution on an IP address fails because the domain doesn’t exist. Yes, ISPs sell this data. I personally talked with a representative that gave me her business card and quoted me a six figure number for access to their NXD data. These domain name research companies actually buy this data and register those domains to see what generates money. Their hope is that if people at one ISP represent 1/5000th of the Internet, they might receive 5000 visitors a month from all the other ISPs around the world according to that ratio. So by testing a theory with DNS, people are telling these companies what domains to ‘taste’. Ironically, this type of behavior will have a chilling effect on direct navigation which actually hurts the domain parking industry as a whole...

I suspect the problem is overstated, but I'll personally avoid testing out my domain ideas through the address bar ...