Ananova do not recommend using shared web hosting to run an ecommerce store for two reasons.
One, when you are sharing the server with other websites those sites can cause your pages to load slowly or even the entire server to crash. The second reason is that a shared server is a lot more susceptible to security problems and when you are running an online store that is charging and possibly storing credit cards that is not safe.
The Dangers Of Using Shared Web Hosting For An Ecommerce Store:-
Performance Concerns:- If you are running an ecommerce store you want it to be online near 100% of the time for both your customers and so search engines can find it. If you are down it can cause users to not trust the site and the obvious downside that they can't buy anything. Similarly if search engines come across your store and it is down that can cause problems for the search engine optimization you are doing.
Security Concerns:- In a shared hosting environment you are more susceptible to security problems which is a big problem when you are running an ecommerce store. Shared web hosts usually make a profit by volume and not quality, this might mean they don't have time to make sure all their servers are fully secure. You don't want to wake up one day and find out that another user on your shared server was reading your files and got your database password and has all your store's info and customer list.