I think if one is going to assert facts, then yes. One should be accurate in the presentation of said facts. The unfortunate reality is that facts are not always presented accurately, or are sometimes twisted or slanted to support an argument, or chopped up. When reading ANYTHING, before we accept anything stated as factual, we have to do our own research to validate it.
Slanted websites should always be read with some skepticism. Daily Kos for example which leans left. Or the Huffington Post. They may use facts in accurate ways, but not use them in genuine ways if you know what I mean.