Can artists refuse a commission because they don't like an idea?

[friskecrisps.livejournal.com]

Had this happen a few times over the years and just got to thinking about this. Can artists refuse a commission because they don't like an idea? I mean yeah I know every artist has the right to refuse commissions, but if its not posted in their terms of service or on a list on their page saying they will/won't draw certain fetishes, then can they just say I don't like said idea so I won't draw it. I'm sure this might be coming off as a dumb question but it just seems that through this way, a commissioner has to bend more to the artist's way of things in order to get a commission done by said artist. That if the artist doesn't enjoy drawing the pic, then its not worth doing.