Brush up on cleaning
What’s ‘dwell time’? Most spray-on cleaners need to sit on the bike for a time, so their chemicals can break down the dirt. This is the dwell time. Check the directions for use.
Does scrubbing make a difference? Absolutely. Every product can give good results if supplemented with a sponge and elbow grease. Most suggest areas of heavy muck should be agitated (gently moved with a sponge, rather than fiercely scrubbed) before being allowed to dwell. Some thicker sprays may need spreading out anyway, to ensure coverage.
What happens if a cleaner dries on the bike? With some cleaners, nothing… but others may stain vulnerable materials. Read the instructions and if they say “do not let dry” or similar, keep the hose handy.