We Don't Own Our Servers
A lot of web hosts, even many popular web hosts, do not own or control the servers that they sell space on. Many of these web hosting companies are simply re-sellers for other web hosting companies. You are simply paying a middleman extra money and possibly slower support response time.
Unlimited Bandwidth Definitely Does Not Mean Unlimited
Many web hosting companies lure customers in with low cost hosting that has no bandwidth limit. They advertise that you can use as much bandwidth as you want to, but hidden deep in the legal terms of authorized use they mention that you have a "node" limit. You node limit may be 100,000 or even 250,000 which are common node limits. Every individual file, graphic, email, and HTML file on your web page uses 1 node.
It is very common for people to surpass their node limit. While you may think that you have unlimited bandwidth it will be very possible that the company will shut down your website or force you to pay extra money for passing their node limit. Every email you receive also counts as a node, so if you get a lot of spam and don;t have time to delete it then your website could easily be shut off by your cheap web hosting company.
Oversold Server Space
Many web hosting companies that sell cheap web hosting places more websites on a server then it is designed for. In theory many of these websites may not get a lot of traffic, so they can often get away with this. The problems begin if one of the websites has an article that goes viral or suddenly gets a large amount of increased traffic. The increased traffic for that individual website will then slow down all of the other websites that are hosted on the same server.
It is very common for cheap web hosts to throttle your website. They will throttle it which means your website will slow to a crawl. Bandwidth throttling is an easy way to minimize congestion on servers that the company has oversold space on. Many times hidden in the web hosts terms of service they will mention that if your website uses to much of a CPU load then they can legally throttle your website.
Server Up time Guarantee
Many web hosts have a server up time guarantee. Hawk Host and others have a great server up time guarantee where they will reimburse you for any downtime. The higher the percentage of downtime then the more they will reimburse you. Some web hosts such as Hawk Host heavily advertise their up time guarantee. The problem is that you need to file a report and send it to the host in order for them to reimburse you. If your website goes down and you are gone camping for the weekend then you may not of even know that you website was down. Even when you do fill out the forms and send them in to be reimbursed the web host companies often have legal maneuvers they use that keep you from getting paid back for their server downtime.
I can however vouch for Hawk Host. It is annoying that you have to send them information to get paid for their downtime. I have only had to do it with Hawk Host once in 4 years, and to their credit they did give me my discount for their downtime that had occurred.
All web hosting companies have terms that explain what they allow and do not allow. Many web hosts do not allow adult oriented content while other web hosting companies specialize in selling to adult webmasters. You need to thoroughly read through their terms and then email them if you are unclear on any aspect of it. You need to know if the web host will allow your website or not.
As an example what if you are a website that shows pictures of breast cancer. Some hosts would allow it because it is not intended to be adult material, however other web hosts will ban you for an pictures of bare breasts even if it is not of a pornographic nature.
Many web hosts, especially small re-sellers, will happily tell you something is allowed when in fact it is not. They will simply get as many payments from you as they can until the company that actually owns the servers discovers it and then your website will be shutdown and you will once again need to move hosts.
Once you find a good cheap webhost that you are happy with then stick with them for all of your future needs. It feels good when you have a good working relationship with your webhost. They will strive to help you out and you can trust their webhosting advice.