How do I copy sellers?

I have been looking at certain auctions in Ebay, and certain sellers seem to sell nearly 100% of their auctions. Whereas, I am lucky to sell 20%.

On the surface, I dont seem to be doing anything differently to them. So how do they sell 5x as much?

Is it possible they are getting traffic to their auctions, outside of ebay? If so, how do i find where they are advertizing etc?

Any blackhat methods they use?

alot of it depends on their seller rating and feedback, people are more likely to buy from a better ranked seller. also they might have store that they link to from their website rather than selling directly using a shopping cart