I was just writing a WhatsApp to ask someone to check who a jacket belongs to.
"Could you check if this jacket belongs to anyone?" sounds like a friendly request. I'm asking her to do it.
"Could you check if this jacket belongs to anyone, please?" sounds like an instruction - polite enough, but I'm telling her to do it.
"Check if this jacket belongs to anyone, please" sounds like an order.
The word 'Please' doesn't necessarily make a sentence politer. It may do the opposite.
