How can my boyfriend find out if his parents like me?

So I know they don’t like me just from how they act, never ask me about my life and just say rude things to me about what I wear/eat etc. I have been itching but nice to them. This has been going on for 5 years. I’m over it and it barely bothers me but what hurts is when my boyfriend tells me that his parents love me... clearly from how they act when I am around they don’t. I don’t know if it’s different when I’m not there or is he just so oblivious to it? Today he said he was going to prove to me that they like me by texting his mom and showing me her reply. I told him not to since that’s so obvious but at the same time am curious about what she would say. Is there a way for him to discreetly ask?