I think alot of them are acidents, OOOOPs! catch dog got with the strike dog........and then U say "I meant to do that", atleast last time it happend to me, I did

!
Seriously, I usually keep something from those accidents, just to see what they turn up as, and have been fortunate! I also believe my good fortune, helps that the dogs on the yard that got together are always good dogs in their own right, if I don't keep junk from the start, well then when the accidents happen, they atleast have the genetics to be good.