What's bad? They're a waste of the world's resources and completely pointless. The only thing you need to clean a visor is water, kitchen towel and five minutes.
If your visor is caked in insect debris you could use a spot of washing up liquid.
Place the smallest amount on a towel (tear resistant ones are best), wet the towel, squeeze out the excess water, fold in half, neatly press onto the visor and leave for 5 minutes. The flies lift off without rubbing.
I guarantee that once you've tried this method you'll never buy one of the useless little bottles again. Need to clean your visor away from home?
Just stick a couple of sheets of Bounty in your jacket pocket and stop at petrol stations for water.
What's good? Nothing, zip, zilch
Rating: no stars
Solvent based visor cleaners, from £2