How useful is web hosting with unlimited disk space and bandwidth?

Most web hosting companies nowadays are offering hosting packages with unlimited disk space and bandwidth. While such limitless features do look very attractive to hosting customers, but they come at the cost of web hosting quality and performance.

How is it possible for web hosting companies?

Web hosting companies often promise unlimited hard disk space and bandwidth but in reality, they are only using it as a ploy to fool their potential customers.
They will most probably disable customer accounts once they reach a certain limit set by the web hosting company. This limit could be anything from a few hundred MBs to a few GBs of space and bandwidth.

Quality of unlimited hosting:

When web hosting companies remove the space and bandwidth restrictions from their hosting accounts, it leads to a very heavy load on their servers and it affects the performance of web hosting accounts located on those servers.

Some hosting companies claim to allow unlimited space and bandwidth only under certain terms and conditions like allowing only non-media files, but even then some customers manage to fill up the disk space through allowed file types and databases which leads to poor performance of these servers.

A list of well known hosting companies providing unlimited hosting space and bandwidth:

1. HostGator.com
2. Hostmonster.com
3. Fatcow.com
4. Bluehost.com
5. ixwebhosting.com
6. JustHost.com
7. InMotionHosting.com
8. iPage.com