I find that when it comes to stuff like reviews (including, but not limited to photography equipment), you probably don't want to put all your eggs in one basket for anything important.

If you look at two or three (or more) reviews, however, you should start to see some common themes emerging -- ie, the lens is soft wide-open, or it focuses slowly, or it's got great bokeh -- whatever. To the extent you start to see these attributes come up time and again for a given piece of equipment, you can start to be pretty sure there's something real there. If you do this a few times, you'll also start to have a good frame of reference for how reliable any given source of information is; so in the future, you'll have a pretty good feel for whether you want to start with Ken Rockwell, or whether you'd be better off starting with someone like DPReview.

The idea here is that any given review on even the most trusted site could be off, so don't rely on a single source of information unless it's a purchase you're comfortable taking a gamble on.