It seemed to me that she, and other people posting in her comments, believed that relativism meant thinking that all views in the world were equally true -- and, this being so, for someone espousing it, it wouldn't matter what you believed, so how could you decide?
It seems to me that actually, relativism is rather the belief that all views are equally valid, and that most sensible people would argue that there are certain areas in which relativism is applicable and certain areas where it isn't. Morality and ethics are areas where it is, and science, for instance, is an area where it isn't. Or, specifically, anything where there are grey areas, where reasonable people could hold different opinions, such as whether doing something is right.
There's an old joke about the skeptic being asked what colour the horse is and replying "It's white on this side." A pure relativist, if there were any such thing, would, I suppose, reply "I see it as white..." but be accepting to others seeing it as blue, polka-dotted or a cow. But in reality, there isn't much room for reasonable differences about what colour a white horse is, and not even the most convinced relativist in the world would say there was.
When it comes to what is good, where there's a huge ground people have been arguing over since Socrates, then saying your ideas are just as valid as mine, even though we disagree, seems quite sensible. It isn't to say I'm about to lay down my own ideas and take up yours, Fred's or Mrs Evans's. It's that in areas where it's reasonable to disagree, I'll allow that it is reasonable.
I think there are some areas where everyone's a relativist. Taste, for instance. My lovely welshcakes might seem tasteless and dry as dust to you, and neither of us are lying, it's just what we like. And there are people who voluntarily eat curry.
I think the problem arises with areas that to some people are as indisputable as the colour of this side of a horse and to others are very disputed indeed -- like for instance religion. I've seen very firm believers and very firm atheists claim that there is no ground for disagreement from their position.
Relativism isn't the sort of belief people go to the stake for. Like moderation, there are very few fanatics leaping up and insisting everyone allows everyone's opinions validity or else! It doesn't give certainty -- far from it -- and people like to feel sure about things. There'll never be a crusade for it.
Where it wins, I think, is not only in politeness and getting along with people with different opinions, but in encouraging open minds and consideration of many sides of complex questions. Where it doesn't is where you have minds so wide open everything falls out -- or with things like the supposed post-modern consideration of a scientific paper on purely textual grounds.