Sometimes they will accept no blood at all, not because of outdated viewpoints but because they are forced to decide (in front of Brother Hounder) ahead of time which, if any, fractions they will and will not accept. Then, when the real thing happens, they are held to their vows (anyone that vows something bad for himself and keeps same vow is righteous in their eyes).
If they decide to accept fractions, they are afraid that they will look bad. Remember, they do not get to do this in private. The hounders have to sign the card, and once it is signed, it cannot be changed. They will not sign it if it is done in pencil or erasable ink--you must use regular ink to fill out the card. This ensures that the hounders will see what fractions you will or might accept. If you might accept fractions, they have the ability to gossip about you and hound you on other trivial things, and give you the stumbling-others speech.