Some people tell me your not suppose to let the bass's skin hit the ground because it loses its slime and the fish can get infected. Others tell me you shouldn't grip the bass by the lip and hold him up, because it damages their lip. I just wanted to know are these things true? What is the right way to hold a bass? I usually just grip him by the lip, or lay him on the ground for a quick 10secs to snap a picture next to my foot (so you can tell the size, kinda)

Try never to touch his skin - holding bass by the lower lip is the best way to go, but if the fish is large, don't hold him horizontally by the lip.  This could damage his mouth/jaw.  All the things you hear about the slime are true - touching the body of the fish and especially laying it on the ground could make it vulnerable to infection.  

I know with some saltwater species like tarpon you're not supposed to hold them up by the lip alone, but for bass it's the best way.

Do all you can to not disturb the slimecoat on the skin and NEVER interfere with the gills.

Best way is by the lip, up and down, like this

If you are going to hold it sideways,..ALWAYS support the belly, like this

It is this second style where people mess up and do damage.  If you DON'T support the belly, you can easily break the jaw.  I'll hunt around for a "wrong" pic-anyone, any help?

NEVER stick your fingers in the gills!

Never stick your finger in the hole right after the 2 fins on the bottom! Thats worse for you than the fish

Actually the photos are not all that good. You shouldn't bend the basses mouth open and should turn the bass upside down or belly upwards if the bass is good size. This does two things, the bass freezes and stops trying to flip around and it prevents bending the lower lip excessively. Supporting the bass by it's under side for a photo is good, just try not to bend the down.

Lay the bass on a wet towell and use your rod if you need to take a photo for size reference.

WRB

LBH no problem with the way you are holding the bass. I was taught Never ever to put a bass on anything absorbent, wheter yu wet it or not, especially a terrycloth towel, as the fibers will cause microscopic tears in the slime covering, leaving those areas defensless against bacterial and fungal infections.

NEVER stick your fingers in the gills!

What about reaching through them to turn a hook when the fish is hooked in the gullet.

Which will do the least damage?

Moby; I would try my best with a long, narrow needle nosed pliers , rather than my fingers.I have used my fingers with disaterous results on one fish. I gave him to a guy on shore fishing for a mela, as he went belly up and was leagal keeping size.