Take a bottle of Bud (hopped to just below threshold i.e. around 14 IBU) outside on a sunny day and leave it in the sun for half an hour or so. Then take it inside, chill it and open it. I'll leave you to decide based on this whether you think lightly hopped beers are subject to skunking. The last time I did this for a class they could smell it in the back row as soon as the top came off.
The reaction is diagrammed (from HBSY) at
http://www.pbase.com/image/126112195. In the diagram a photon (hv) knocks the side arm off an isohumulone molecule at the dotted line in 71. This reacts with sulfide or any mercaptan to form isopentenyl mercaptan (98) and it is this that smells skunky. The diagram also shows how isohumulone can be reduced by sodium borohydride and the result (97) is supposed to be less susceptible to cleaveage than (71) so some breweries use reduced, pre-isomerized hop extracts for their bittering. If AB happens to be one of those you might not get the skunked effect (it's been quite a while since I did this demo).
