Scamming Sephora? Return an expensive foundation/ mask/ perfume/ etc with a cheap version while having deported original?

For example: say you purchase the la mer or Tom ford ($80-110) foundation and depot lt to a small glass bottle/ just a cheap plastic bottle, then replace the product with a cheaper alternative like revlon ($8) and seal the product. Sephora has a policy of returns for gently used products, which they accept! So would this work? Are employees trained to check the bottle or scent of a product?

It definitely does work, many people have done this