The idea behind bud washing is to remove all the dust, dirt, your skin cells, etc from the plant. Even in a "clean" environment, there's still tons of dust and crap floating around. In my case, my cat thinks she owns my grow tents so everytime I open them, she runs inside and starts purring. Crazy cat.
Anyway, there's different variations of the process but the one i'm familiar with involves 3 buckets, baking soda, lemon juice. You put the lemon juice and baking soda in the first bucket with room temp water. Swirl around your fresh chopped cola in the solution for a bit and move it to a 2nd bucket with hot water. Same thing, swirl it around like you're trying to clean it without touching it and letting the water do the work. The 3rd bucket has cold water in it, same thing. Hang and dry, then cure.
I haven't done the process yet but I plan to with my next harvest coming up in 5 weeks or so. I plan on doing just plain water. Room temp, hot, and cold. The baking soda and lemon juice scares me. I'm worried it may change my flavor profile despite people saying it doesn't. Maybe I'll experiment with a smaller cola with the baking soda and lemon juice.