it's never impolite to refuse alcohol.
the problem with beer is thus. cheap rum still tastes like rum.
cheap beer tastes like fizzy piss in a can.
people who "dislike beer" are overwhelmingly referring to pale lagers that make up the bulk of the stuff you'll see in a cooler at a picnic. it is bitter by intention and most people are only exposed to the low end.
porter/stouts (guiness being a big name) are my personal preference.