And the award for this weeks daft question goes to........
Seriously, any liquid around anything electrical is a big no no

. Beer, just like water can conduct and create short circuits and a risk of damage to either the speaker or amp driving them.
Yes, I have known the majority of speakers survive small amounts of beer spilled on them, but like running an electrical item next to a bath, its not something you'd encourage or risk.
Speaker cones are made of material, which is treated, however like cardboard they can still absorb liquid and the preformance become impaired because of it. If you spill a large amount of any fluid onto a speaker cone, better to repair it as soon as economically viable.
Yes, (a lot of) damp can damage and discolour speaker drivers, as it can also corrode the circuits in crossovers and the coils in compression drivers and loudspeakers over a period of time.