side affects of not re-installing bearing shields after cleaning?

Side effects would be more subsceptible to get dirt and debri inside the bearing.

I've been using Boca O.S.  spool bearings without shields for over a year now with zero problems, but I do clean them alot more than shielded bearings.

I removed the orange seals from my ceramics early last year when I installed them.   I kept an eye on them and ended up only having to add a tiny drop of the Oust Met Oil I use occasionally.  They stayed surprisingly clean.  I carry a needle oiler in my gear if needed and you can get them here very inexpensively.

http://www.brownells.com/.aspx/pid=1200/Product/NEEDLE_OILER_BOTTLES

I also run OS Ceramic bearings open.Even though the seal is a "non-contact" seal, I get better performance with them open. Certain model reels come with open bearings stock. They are not a problem if recommended service schedules are kept.