I cleaned a bearing for the first time a couple of weeks ago and had a terrible time removing the shields. Switched the pin to my right hand and it came off first try. Coincidence? Who knows?
Most of the c-clip springs that hold the shields on are made with the same orientation of the bevelled edge of the joint. That orientation provides a bit of a lip, so to speak, that a pin in the right hand can grab on to. Of course some bearings may be opposite so you will have to look carefully to see which end to work on.
Take a look at the images here: How to deshield a bearing
. The second and third image show it best. They are attached below for convenience.