I have been carrying a S&W Shield in a deep concealment holster when OD for about a year now. I opted for the Shield due to it's fantastic trigger, trigger reset, and durability. I've been using Frog Lube (after stripping original CLP) on the gun since it was new and haven't had a single issue with it. I even gotten it very dirty (shotting a lot of dirty ammo), then carrying it for awhile without cleaning, and shooting again while dirty.
Even with cheap ammo I've come to realize my Shield is one reliable gun. I simply can't get it to malfunction.
Not everyone agrees with me "breaking-in" my guns by torturing them but I have to depend on this weapon. Now when I shoot it and clean it I know it will perform as intended should the need arise. And...It's a gun, a tool, and not an item I use to impress my friends.