Ardent is a known company but generally companies do not go solicit the general public. On the other hand there are scammers who spoof legitimate companies to try to trick you out of your money. A legitimate company does not send you money in advance of a shop to cover your 'fees and expenses'. Generally a mystery shop pays $5 to $15 with a small reimbursement and this is likely to come 2 weeks to 2 months after they have accepted the shop.
Another common scam in the last few years is to have "you" buy gift cards at a store (sometimes any you like), text them the codes from the card, and promise reimbursement and a fee. The poor would-be mystery shopper will never see a dime.
Shopping Southeast Pennsylvania, Delaware above the canal, and southwestern NJ since 2008