A discount only means something relative to a price. When the reference price is one that nothing was actually sold at, the percentage describes nothing.
This is a well-documented practice with a regulatory history, and knowing the mechanics makes it visible.
How reference pricing works
A retailer displays a higher price alongside the selling price, described as recommended, original, or a comparison figure.
The saving is calculated against that reference.
The question that determines whether the saving is real is whether the reference price was ever charged, and for how long, and where.
Where an item was offered at the higher price for a meaningful period in the same shop, the discount is genuine. Where the higher price is a manufacturer's suggestion nothing sold at, or was charged briefly to establish a comparison, it is not.
The regulatory position
Which has tightened considerably.
Consumer protection authorities in several jurisdictions have taken enforcement action over misleading reference prices, and rules commonly require that a comparison price must be one at which goods were genuinely offered, for a defined minimum period, within a recent window.
Some regimes require the reference to be the lowest price applied in the preceding period, which specifically prevents a brief price rise before a sale.
Enforcement is uneven and the practice has adapted rather than stopped, generally toward comparison against a manufacturer's suggested figure, which is harder to challenge because it is not a claim about the retailer's own past pricing.
Price tracking as the answer
The practical remedy that removes the question entirely.
Browser extensions and websites record the price history of individual products at major retailers, showing what an item has actually sold for over months.
Which converts a claimed discount into a checkable fact in about ten seconds.
What the histories generally show is that many items on prominent sale are at or near their normal price, and that the genuine low points frequently occur at unremarkable moments rather than during promotional events.
The tools are free, and using one before any significant purchase is the single highest-value habit in this whole area.
The pre-sale increase
The specific pattern the rules were written to address.
Raising a price shortly before a promotional period, then discounting from the raised figure, produces a large advertised saving with a small or no real reduction.
Consumer organisations have repeatedly documented this by tracking prices ahead of major sale events, and the findings have been consistent enough to be unsurprising.
Price history tools make it visible immediately, since the increase appears as a spike shortly before the sale.
Manufacturer suggested prices
Worth understanding since they are the most common reference.
A suggested retail price is a figure proposed by the manufacturer, and in many categories nothing is routinely sold at it.
Which means a discount from it is a discount from a number that functions as a marketing device rather than as a market price.
It is not dishonest exactly, since the figure exists and is disclosed as a suggestion. It is uninformative, and it is presented in a way designed to look informative.
The urgency devices
Which accompany the pricing and work on the same principle.
Countdown timers, stock level warnings and viewer counts create time pressure, and regulators have taken action where these were found to be fabricated or misleading.
Some are genuine. Many reset when the page reloads, which is a straightforward test.
The purpose is to prevent the ten seconds of checking that would reveal the price is unremarkable, which is worth knowing as the reason they exist.
What I actually do
Check the price history before any purchase above a trivial amount.
Ignore the percentage entirely and look at the absolute price against what I would pay.
Treat urgency indicators as a signal to slow down rather than hurry, which is the opposite of their intent and is the correct response.
And maintain a list of things I actually want, so that a genuine low price on something I need is recognisable, rather than being persuaded by a discount into wanting something.
That last habit removes more unnecessary spending than any amount of price comparison.
Personalised pricing
A development that makes comparison harder still.
Some retailers vary prices by customer, using browsing history, device type, location and inferred willingness to pay.
The practice is legal in most jurisdictions with disclosure requirements in some, and it has been documented in several sectors including travel and electronics.
Which means the price you are shown may not be the price somebody else is shown for the same item at the same moment.
Checking in a private browsing window, or from a different device, occasionally reveals a difference, and where it does it is worth taking the lower one.
Dynamic repricing
Separately, many online prices change continuously through automated repricing against competitors, which is why a price observed in the morning may differ by evening without any promotion being involved.