It will only ever be a small percentage of good stuff ladies, because retailers don't buy stock to markdown for sale, they only buy it to try and sell at full price. Therefore the "terminal stock" as it is called when it goes down into markdown, tends to be made up of:
Odd sizes that don't have a large target market, ie 6,18,20 and the same with shoe sizes.
Worst sellers when they were at full price - because they misjudged a fashion trend, for example, or a lot of the time it is because a capsule of items doesn't all make it in from the far east and the few items that do just look a bit odd and unsaleable.
The display stock, when you buy stock for retail you buy a display quantity eg one of each size to remain in the store at all times to sell from, if it isn't carried over to the next season it will be marked down.
As a retail planner, I would be seriously flailing my team if they had overbought in a uk retailer and had to spend millions to mark product down as it really affects the planned profitability of the business.
Luckily I am in an international firm who are doing ok at the moment, but it is a bloody hard job getting the balance right, but yes, things aren't usually in the sale because they are bestsellers. If you are a good retailer, only 5% of your total buy maximum of bestsellers should end up in the sale.
So the odds aren't very good I am afraid.
I run outlets now, and I can say footfall has been very quiet over the last month, so they may be running some amazing promos to try and get the customers in and spending, particularly if they are out of town sites.