Some beauty products make claims that are clearly exaggerated (73 per cent longer lashes, anyone?) but there are certain sales pitches that sound plausible enough to impress.

However, when you unpack these claims, you will likely find that - though they may indeed be true - they aren't really saying anything.

Here are some fairly meaningless examples:

"This self tanner works with your skin's natural melanin."

All self tanners (as opposed to wash-off bronzers) contain dihydroxyacetone, or DHA. This is the active ingredient that reacts chemically with the amino acids in the skin, causing it to turn brown.

Some self tanners contain naturally derived DHA (eg. from sugar cane) and others manufacture via by a chemical process. But every self tanner on the market does what this claim says - rendering it meaningless when comparison shopping.

"This eye shadow can be used be used wet or dry."

Unless it's a loose powder or a cream, we'd wager that any pressed powder eye shadow can be made to look darker simply by dipping the sponge applicator in water.

"This foundation can be layered to customise your level of coverage."

Perhaps pancake makeup from the 50s couldn't perform this simple feat, but other than that we're pretty sure you can build up any foundation product to make it give more coverage.

Want less coverage? Apply with a brush or mix it with a bit of your usual moisturiser.

"This hair product can be mixed and matched with other products from the range."

As far as we're aware, the sky hasn't fallen when we've used one brand of shampoo along with a different conditioner or styler - and even less so when we've stuck within the same brand family.

Unless you are mixing very active skincare (such one containing retinol), it's always fine to cherry pick your products.

"This skincare is chemical-free"

Everything is a chemical. Water is a chemical. All matter is made of chemicals. This claim is therefore an impossibility.

What the makers usually mean when they say something is 'chemical-free' is that it's free of industrial or man-made chemicals and contains natural or naturally derived ingredients.

While opting for natural cosmetics is a personal choice (often made for environmentally conscious reasons), bear in mind that, as Roger Highfield, science editor for The Telegraph, puts it: "Whether a substance is synthetic, copied from nature or extracted directly from nature, tells us nothing much at all about the dangers it poses."

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