Can braid be used effectively on a spinning reel? Do you use backing (mono or anything else) to make a base on the spool to keep the braid from digging in?

I use Invisa-braid on mine. Works great. I did back spool but to save line mostly. I love it!

Yes you can use braid on spinning reels and you do not need backing. All line will dig in when you snag and with braid it is best to wrap the braid around something like the pliers handle when trying to pull out a snag. Wrap pliers and point the rod directly at the snag then pull till the hook bends or the braid breaks.

I have a spinning reel spooled with braid whenever I fish lakes with grass or lots of wood. Right now I'm fishing Ray Roberts with 8/30lb braid and a 4' 15lb fluorocarbon leader. I use it for weightless rigs around cover.

I am using Power Pro braid on one of my spinning reels for a trial. I also use mono for a little backing. I just started using it on the spinning reel this year and so far I like it. It seems it does not have some of the problems mono has that causes some tangles on spinning reels. I am using 20# with 8# diameter. Like I said, so far - so good.

This is true, but strength isn't the main reason to use it on a spinning real. Braid cast about 100 times better than fluorocarbon on a spinning reel.

I agree with that! I can't put 15lb on this reel. It works best with 10lb and 12lb at the most. I use the braid so if/when a fish wraps me around something the line won't snap. Remember without braid I'd have 12lb line wrapped around the stump in the middle of a grass bed and that rarely works out well with a big fish. The braid is for the strength plus abrasion resistance and the leader is cut down on the line visibility.

It doesn't loop like mono or floro when casting.

i use 2' of mono backing to keep the braid from slipping on the spool... then i wind it on TIGHT! if you do that, it resists digging in AS MUCH. i use to fish with 30# braid on spinning reel for fishing under docks.

Use a line conditioner it does help with the "digging in" problem. I also use a mono backing for two reasons, it keeps the braid from slipping and it saves money on the braid by not having to use so much to spool up.

I have used 30 lb Power Pro on my spinning reels for a long time. I use a mono backing to save money. "Digging in" is not a problem as long as you wind it on tight when you load your reel and use baits heavy enough to overcome the "strike bury" on your first cast after a fish.. Used to live in south LA and caught a lot of specs and redfish without a problem.
I have found that Power Pro works better than Spiderwire because it is stiffer and less likely to wrap around the rod tip when you have a slack line for whatever reason.
Since the only time I use spinning reels is when I fish for sandies, I use a FC leader so I can easily tie a dropper loop for a fly above a slab. The knot is a weak point and I'd not use it otherwise.

I've been using 15lb Power Pro with backing for some time now. I use a flourocarbon leader that is 4 to 6 feet long and I've caught fish up to 7 lbs with this rig. One of them from a tree that took a minute of manipulating for the fish to come out of.

I've just put some 12 lb on a new light weight setup and plan to use it with 6 or 8 lb 100% Berkley flourocarbon.