Padre targeted by unions: but are they effective?

The new Padre Hotel became the latest in a long string of local businesses (including The Californian several years ago) to be targeted by organized labor for allegedly using non-union workers or paying prevailing wages on contracts. The problem for the union: these "shame on" protests have become so common they no longer draw attention, so to my knowledge are ineffective. And my guess is the folks they hire to stand behind the signs all day are not being paid "prevailing wages."