2. A cloudy, permanently smeared shower screen
Glass in a hard-water area picks up two things: mineral deposit, and a layer of soap scum bonded to it. Cleaning one without the other leaves the screen looking no better, which is why people conclude the glass is “just like that now”.
Do the scum first with a degreaser — washing-up liquid on a cloth, or a bathroom spray — and rinse. Then do the minerals with citric acid solution or a proper limescale remover, left on for fifteen minutes before you squeegee it off.
For a screen that has been neglected for years, the deposit may have etched into the glass surface. A fine glass polish or a cerium oxide compound rubbed in with a cloth can recover it; a scouring pad cannot, and will scratch. If the glass stays hazy after both treatments, it is etched, and replacement or a shower curtain is the honest answer.
Prevention is the whole game here. A £6 squeegee hung inside the shower and one pass over the glass after each use keeps a screen clear indefinitely, and it is the single most effective bathroom habit in a hard-water house. It takes fifteen seconds. Ventilating the room afterwards — window open or extractor running for twenty minutes — does the rest.
Do not stop at the glass. The plastic channel along the bottom of a screen and the rubber seal strip clipped to its edge hold standing water between showers, and both build a grey mineral and soap deposit that keeps re-contaminating the panel you just cleaned. The seal usually unclips by hand for a soak in citric acid solution, and replacement strips cost about $10, CA$14 or £8 for a two-metre length if yours has gone brittle or yellow. The channel is worth drying with the same squeegee pass you give the glass.
Skip the rinse-aid and car-wax tricks circulating online. Some work briefly, but wax residue in a shower tray is a slip risk that outweighs the shine.