thats to do with your presentation layer, where you actually use the data, rather than where you store the data.
Although it can be attractive to store the number as 03, or dates as 02/05/2007 it often becomes a real pain when it comes to sorting or manipulating data.
if you store numbers as text then you have to store every number in the same manner, you have to know the magnitude of the number range so you can pad numbers accordingly with zeros or spaces other wise your sort order is banjaxed eg 1,10,11,12..19,2,20...29......
if you store dates as text its very difficult to say find rows in a specific period
say you wanted to compare sales in May for the last 5 years, or you wanted to analyse sales in the first 7 days of a month... you loose the ability to use the MySQL date functions
moral of the tale, unless you have a really really good reason store values in the most appropriate datatype, handle formatting issues in the presentation layer
I'd rather be riding on the Tiger 800 or the Norton