It's important to remember that publishing on the web is very easy - almost anyone can do it! The problem with that is knowing what's credible (worth your time) and what's not.
Here are some of the thing you want to look at or for:
the URL (.gov, .mil, .us, .edu are usually pretty credible);
links to information about the author or sponsoring organization;
links to other sites that are credible;
how current it is
Ultimately the researcher must be the one to determine whether or not to use information found on a web site. The following information from Cornell University provides some excellent guidelines for evaluating sites (link is below).