It's up to you to check for bias and to determine objectivity. Look to see if the page owner tells you when the page was last updated. Try to distinguish between promotion, advertising, and serious content. This is getting to be more difficult, as an increasing number of pages must look to commercial support for their continuance. Watch out for deliberate frauds and hoaxes.
Some folks really enjoy playing games on the Web.
There is no way to freeze a web page in time. Unlike the print world with its publication dates, editions, ISBN numbers, etc., web pages are fluid. There's no bibliographic control on the web. The page you cite today may be altered or revised tomorrow, or it might disappear completely. The page owner might or might not acknowledge the changes and, if he relocates the page, might or might not leave a forwarding address.