So you'll take gay dollars if the subject matter doesn't include gay people but you won't take gay dollars if the the subject of the painting is gay.
Hipocracy always go part and parcel with bigotry.
I think this is a civil rights issue. If gay marrige is legal, the people getting married have the legal rights that anyone else getting married has. I think these bakeries who refuse to make a gay wedding cake should have to advertise that fact up front in their advertising material and post it prominently on their shop, inside and out. Then, at least people would know who to stay away from. If I were gay and getting married, I would not want to patronize such a bakery. Also, as a non-gay person, I would also not want to patronize such a shop on grounds of principle. And, when these bakers make their position known, admit what they are doing, it makes it easy to prosecute them on grounds of civil rights violations. If you want to be in business to the general public, you have to include everyone, whether it is about gender, race, lifestyle, ethnicity, etc. Doesn't matter.