Here's a quick one.
The Problem: When inserting a table into the descriptions field inside the admin area of a Magento store the output creates line spaces - resulting in 'br' tags on your page.
The solution: you need to take the spaces out of your code
for example you may have
<tr>
<td>hello</td>
</tr>
<tr>
<td>world</td>
</tr>
you'll need to change this to
<tr><td>hello</td></tr><tr><td>world</td></tr>
Then you will not have any spaces in the output. Just a very confusing view of spaghetti code to work though in descriptions tho.