When i was being paranoid about Eliza being dehydrated i would frequently bathe her in the kitchen sink, i plugged the drain and put a towel to cover the whole bottom of the sink, got it soaking wet with warm water (i didnt fill the sink any- the towel was just soaked) and put her exoterra cave in there. i left her there for about a half hour (i didnt want it to get too cold). the sink is tall enough so she didnt escape.
No need to bathe them. They're desert animals, and wouldn't frequently come upon enough water for a bath. They don't tend to like it. Of course, if you've got a really dirty leo (like he walked through fresh poo and got it all over) then it won't hurt.
No, I wouldn't bathe it unless it's covered in poop. Bathing is stressful and unnecessary. Also the gecko can inhale water and get it into their lungs which can cause an upper respiratory infection.
dont bath them there fine unless of course they walk in poop but mine has never done that, and also they shed and can go in their moist hide so i guess that could be considered bathing lol