I've only broke down and bought one lot of "once fired brass" from a gun show.
All of it was 45 acp, all large primers, and about 8% need to be smashed flat with a hammer and tossed in the scrap bucket. A reloader must have been testing a high pressure load. All his S&B brass had signs of high pressure and one had a split case.
Clearly not someone who has heard of getting advice from this awesome forum.
I had to go through the rest of the brass under magnification and even feel inside each case with a probe before I was willing to use the other headstamps. Totally not worth the effort.
If you have to resort to buying your brass once fired, get them directly from a local range. Most ranges give discounted range time with ammo or reloading purchases anyway. Make it a point to get to know the guys who do the brass shoveling.
The range counter guy at my LGS always gives me a discount because I'm either buying supplies or telling him I want to but he doesn't have any of the good stuff in stock =)
The range officers there sweep any brass in my vicinity straight back and let me know they are going to bucket soon, so I can pick through it before they move it away. Even though I don't have to buy brass there, I know through that they sort with screens and again by hand to box by headstamp. Since I also know that they only carry a few brands of 45 or 9, I can ensure that a vast majority of THOSE headstamps are actually only once fired factory loads.