I don't know if these are myths or not, but certainly horrible practices passed down from generation to generation.
1. Using sponges for washing is best.
This is a great way to continue to deposit dirty water and grit under your sponge as you drag it across the surface. Definitely not the best washing tool.
2. Drying with a bath towel is good enough.
Uhm... Yeah, no. The fibers may be soft enough for your skin, but they are pretty coarse on your paint. I've never seen anybody drying with a towel who wasn't using some 20 year old beach towel they no longer had a need for. They never use their best and softest towels, so they are always using something old and crusty. Not a good idea.
3. Using T-shirts to apply wax and buff it off.
Well, I guess if that is all you have... Still not a good idea if you are concerned about your paint.
4. Dealerships know how to fix anything related to detailing.
Definitely not. They are mechanics and not detailers. I've never seen a dealership who employes a professional detailer to handle their cars. These guys are grease monkeys who know how to fix just about anything, but paint is something a little outside their area of expertise. Just because the dealership says they will "detail" your car doesn't mean it will actually come out right.
5. This one is definitely a Myth. Mike will have to come in an explain why, but here we go. Water beading on the surface means the protection is still there.
Not true. Some products sheet water and some products bead water. brand new paint will bead water. Surface tension is what causes water to bead or sheet. Just because it is beading doesn't mean the paint is protected. It could mean several things and is not the only indication your sealant or wax has survived.
I'm sure there are more, but I've got a meeting to get to, so I'm done for now.