For me, it depends on where I find the text, TEd.

If I'm reading a textbook and keep finding errors in spelling then, I tend to drop it as a source or reference. If they didn't check themselves, how can I be sure they checked their facts.

In a personal web page, I assume it was an error when they copied the information...BUT, if it is a personal web page, I won't assume what they're saying is absolutely accurate either. Which means, I won't fight to the death on a point since I don't have an official source of info. (which is why that invented word in the dictionary just pisses me off because they're supposed to be accurate. [still ranting-e] )