As an example in business we dropped all projects under $7K so we complete a lot less projects--our average project price has gone from 12K now to $56K (8 yrs latrer).
It's harder to do this with trading since there is far less confidence in the level of profitability of any individual trade. Anyway, the only reason I can think of to pass on a profitable trade is if we already have too much of our capital in play. I want the bottom 20% as well as the top 20%, otherwise I'm leaving money on the table.