"Bitchpad" is a name given to any website which has a user contributed element to its content, but in which the 'bitching' has reached saturation point and overwhelms the original focus of the site.
For any user-input based site, there is a danger that its users will start to use it as a free public forum for their own gripes and dislikes. Instead of contributing to the site as intended (eg. defining slang terms), they decide to start slagging off anyone or anything they feel like just because they can. Bloated with useless content, the site becomes a bitchpad, populated by people who don't have much to say, so they say it anyway.
Typically, content which classifies a site as a bitchpad can be called pointlessly negative; excessive flaming and complaining are common, but the key element is the presence of unprovoked attacks which are based on personal preference and totally lack any balance or rationality. These attacks are usually directed towards celebrities or bands, but frequently towards other users who do not share the same viewpoint as the bitcher on any given subject.
Spam is NOT a contributing factor. A bitchpad is characterised by conscious acts of wilful pointlessness.
In essence, a bitchpad is a site which has been unfairly taken advantage of; a website which innocently bent over to tie its shoelace but was gang raped in the process.
According to the eminent esociologist Rumgolio Fogg, for any site based on user contributions, the time taken (t) for said site to reach bitchpad status is directly proportional to the users' accountability (a) for their contributions and the difficultly (d) with which contributions can be made. This is known as Fogg's Law, and can be simplified thus: t = ad