I've stumbled or bumbled across something I hadn't noticed before. I didn't realise that when you apply the Merchant filter from the main page it also applies the current "tab" that you are viewing.
I'll give an example - lets say you find a good deal and come to http://www.hotukdeals.com
to post it. The main page has Hot as the default tab so if you then use the Merchant filter it will ONLY show you the Hot deals for that Merchant. I had assumed that when using the Merchant filter it would display ALL deals for that merchant. This meant that I posted a deal that had already been posted (because it hadn't been voted hot enough to show up the Hot view).
I understand (now) that its setup this way is so that you can use the tab views to view precisely what you want for that Merchant but would it not be better to have the default when using the Merchant filter as "New" view? Might lead to less duplicate deals being posted.