Funny that Bronson sells shieldless bearings
As do a lot of other companies, with that growing trend to not have shields on bearings right from the first day you put them on.
At least most of those (not all) do not have any lube in the bearings to start with, so they are already dry, so less likely to attract dirt and other things.
A few companies, maybe the cheaper ones, or that don't really know their product, just have regular bearings that come lubed with no shields, so they tend to get everything in there and get very messy pretty quickly from a few sets I got and passed around for people to try, but the set I put shields on right away actually worked great - just a case of sorting through sets of shields to find some that fit.
The other funny thing is with Bronson Raw bearings, I am sure some people love them, but I have a set here as a person I know bought into the hype, got some, skated them about two weeks and then was over them, as they felt slow and his simple Bones Reds were rolling better than the Raw bearings.
I cleaned them and had them on a board for a bit, but they still tend to not roll as fast as any lubed and shielded bearings, even cheaper generic ones, that I have on other boards.
Just one of those things, I guess.
* If you are going to skate bearings without shields, make sure they are clean and dry, no lube or anything else in there, only a little graphite powder if you want them to last longer.