NEVER, EVER, EVER mass carriers on a terran, without being incredible cautious. I learned this the hard way by getting my ass kicked multiple times. You think that Carriers will desimate any opponent but no if they get locked down.
Here is a way to avoid disaster in most cases. Have these units when you attack
-2 arbiter: have them hallucinated, so there are a few copies)
-Carriers, as many as you want: also halucinate these to make a diversion.
-5-10 Dragoons or zealots: these are for ground support. bring them along with shuttles.
-2-4 Reavers: bring in with shuttles too.
-3-4 Observers: you need detection if you have ghosts and wraiths in the base.
-4-6 Scouts: these are for quick kills of any wraiths nearby.
-1-2 Probes: build in their base when you get the chance and get cannons and shield generators. Recharge your carriers frequently.

This is important, have upgrades. interceptors, damage, shields, armor, recal, stasis, etc. And kill the ghosts as fast as you can!!!!!!!

CreepColony's Opinion: Most Terran players won't built lotsa ghosts unless they are expecting Carriers.