Mystery shopping: see your business as your customers do

Written by Guillaume Pouillier, CNAPS-licensed private detective, licence no. AGD 095-2024-03-06-20190240581 · Last updated: July 14, 2026

A marketing firm’s mystery shopper measures satisfaction; a detective’s detects anomalies. Unrecorded takings, diverted promotions, phantom discounts, ignored procedures: our real-condition visits, documented and dated, tell an occasional error from entrenched fraud.

What does detective-grade mystery shopping add?

An investigator trained in evidence, not a panellist with a questionnaire. They observe and record fairly: actual cashing-up, change given, promotions applied, receipts issued or not, suspicious behaviour, and the findings hold up in French employment law if proceedings must follow.

The difference shows in the deliverable: where the marketing study produces scores, our report produces time-stamped, reproducible, sourced facts, ready to feed a disciplinary file or a complaint if needed. That is decisive when a visit reveals a sale without a receipt or a parallel till: material gathered fairly by a licensed professional keeps its value before the labour court, a satisfaction score does not. For losses already observed, see the inventory shrinkage investigation.

Which scenarios do we run in practice?

The classics: a simple purchase with observation of the cashing-up, a product return or exchange, a discount request, a promotional purchase, a cash payment with change calculated to test the till. And bespoke scenarios: sensitive hours, an employee flagged by a report, a specific internal procedure to stress-test.

Each campaign is built with you: outlets, frequency, scenarios and signals to watch. Repetition is what gives the device its value, a single visit photographs a moment; a series brings out recurrences, and also clears teams when a suspicion proves unfounded. Our investigators rotate (different faces each visit) and operate in Paris boutiques, shopping centres, restaurants, franchise networks and dealerships.

Is it legal to test your own employees?

Yes, under strict conditions: the device must be fair and proportionate, and an employee cannot be judged on a stratagem that pushed them into misconduct. A mystery shopper behaving like a normal customer is accepted by case law; incitement to misconduct is not, the whole value lies in the method.

Two rules govern our protocols. First, the investigator never asks for anything abnormal: they buy, return and pay as a real customer would, any misconduct is spontaneous, not provoked. Second, the employment framework is respected: under case law and article L1222-3 of the French Labour Code, disciplinary use of an evaluation device requires employees to have been informed of its principle, a point we settle with your counsel or HR before the campaign, so the findings remain usable.

What does the report contain, and what can you do with it?

For each visit: date, time, place, scenario played, factual sequence, amounts involved, receipts and supporting documents, anomalies observed. At the end of the campaign: a synthesis of recurrences, the outlets or people concerned, and recommendations to secure procedures.

Use ranges from management to litigation: procedure resets, targeted training, disciplinary proceedings backed by dated facts, or referral to prosecutors where a parallel till is proven. In heavier cases, mystery shopping combines with the shrinkage investigation and internal enquiries, the test visit then supplies the trigger fact that justifies going further. Franchisors: the device also verifies concept compliance and revenue reporting across franchisees.

How much does it cost?

Our assignments start at €85/hour (excl. VAT) (full day €850, volume discounts). Every case gets a free written quote before any commitment, no hidden fees.

A campaign is priced per visit (scenario, duration, purchases reimbursed at cost): a qualification series on one outlet stays well below a classic investigation day. The quote details visits, scenarios and deliverables.

See the full price list.

Frequently asked questions