What you need to do is see how much overture with extension the real domain has. For example, if loans.com has overture with extension of 5013, then you're likely to do good with wwwloans.com.
I wouldn't base my decision about registering a "www" typo based on plain overture for a keyword.
If you have overture w/ ext, there is a better chance of getting type-ins for that name.
I have a couple of loan "www" typos where the domains have overture w/ extension as low as 100 that make me money. Obviously, the more OVT w/ext, the better.
And what I think tetrapak is trying to say is that it's better to register a typo of highpaying keywords such as "real estate" than it is to register something where you probably wouldn't make much per click, like "gaming".