A Mandurah man will front court over scamming a number of busy WA stores with a trick that often results in him pocketing an extra $50 from unaware shop assistants.

Pinjarra Police released a photo of the alleged trickster, and said he seemed to be preying on stores based in the area.

The alleged trickster was caught on CCTV. Credit:WA Police

"The offender enters the store and hands over $50 to purchase a small item," a WA Police spokesperson said.

"He then hands over a smaller note, requesting the original $50 back.