What's a waste of money
Charcoal, purple paste, baking soda, oil pulling, lemon, LED lights sold alone, 'peroxide-free' whitening — rated.
The hacks on your feed, one by one. Some do nothing. A couple are grinding your enamel off. Don't feel bad — the marketing is very good.
If it scrubs, it's wearing enamel
Charcoal toothpaste — stop. Abrasive. Scrubs surface stain off, and enamel with it. Thinner enamel, more yellow shows; net effect over months is darker teeth. Baking soda — same mechanism, same problem.
If it tints, it's temporary
Purple toothpaste — a color-corrector. It leaves a violet film that cancels yellow for a few hours, then brushes off. Fine for a photo, not whitening.
If there's no peroxide, it isn't bleaching
Oil pulling does nothing for color. Lemon, vinegar, strawberries — never. Acid softens enamel, and brushing softened enamel is how people lose it. LED light sold alone — skip. "Peroxide-free whitening" — read the label; it's usually a mild abrasive or a tint wearing a nice word. Pharmacy peroxide, straight — pointless as a rinse; nothing holds it on the tooth.
The one-sentence rule
Scrubs? Wearing enamel. Tints? Temporary. No peroxide? Not whitening.