Thats correct, you must always ask yourself the thousands of experienced domaniers around, why would those names still be available.
Have you checked how much they are to register? and what the renewal fees are?
Dont hand register .com names, watch expiring lists and email existing owners to buy 1 or 2 decent names, then try and sell them, dont go and buy 20 or 50 names until you know what makes a name valuable, your best bet is read this forum from top to bottom for a few months first to learn the industry, its not a get rich quick business. There are bargains out there, but you wont know a bargain until you understand domains and what makes them valuable.
Check out namebio.com and DNJournal.com to monitor weekly sales to understand what sells