Forum Moderators: mack
What you need to keep in mind is that search engines and text readers will read table content left to right across the table, ignoring any column dividers. If you read your text this way yourself and it's a bunch of gobbledygook, that's how search engines will read it. Text readers will, too, which makes it an accessibility issue.
In fact, a friend of mine - also just yesterday - ran her site through an accessibility validator and one of the positives it came back with was that the site didn't use tables. My friend had a very good laugh over this, as her site is filled with tables, often nested ones. But she's careful to follow the rule about having the text readable from left to right, so the validator didn't "notice" that she used tables.
It's not simple to use tables correctly in this way - sometimes not even possible, depending on what content you're presenting - so a lot of people use other methods. If you want to give it a shot, the accessibility guidelines on the W3 site link to some tips on how to do tables correctly.