Let's say you owned deals .co.uk. This is a highly brandable name, really easy to remember, really easy to spell. What it needs is some major marketing campaign to make the most of the name. This is the situation I'm in with LowPrices.co.uk, which is a cracking name, I just need to start a massive advertising campaign.
With regards to deals .org.uk, it has some of the same merits, but it would take a brave guy to invest heavily when someone else owns the .co.uk, and ultimately that really harms the resale value of the name. That and the fact that .org.uk is not as suitable for a major branding exercise.