Camila Cabello and Shawn Mendes Show Haters How They Really Kiss

Shawn Mendes and Camila Cabello are under attack for the way they kiss, so they're letting everyone have a much better look to analyze their style ... and it's sloppily intense.

The kissing couple say they've seen the comments on social media from haters making fun of their makeout sessions -- comparing them to fish sucking -- and Camila confesses it really hurt their feelings.

So, to prove they kiss in a perfectly human fashion ... Shawn posted this extreme closeup vid.

Mission accomplished?

Obviously, the singers -- currently riding the high of their smash hit, "Senorita" -- are joking, but truth is ... they've been locking lips and packing on the PDA during every public opportunity since they began dating in June.

We're talking a coast-to-coast kissing marathon -- from Miami and NYC to San Fran and WeHo ... and even some smooching up in Canada.