I have never read that having an iframe on a page affects that page adversely.

Content within an iframe is not part of that url, it is part of another url. And so a search engine will not be looking at the content of the iframe as an "on-page factor" for the parent url that holds an iframe.

This is an important point to be clear about when using iframes. On its own, that's neither good nor bad -- it's just not something everyone understands because it all "looks like one page".

I'd often wondered about that myself. Many of our items from the same manufactuer have same basic description I had thought about using iframes to display the base description.

I'd thought we might be getting dinged for dupe content even though that information is very important to the customer before they purchase.

Would a bot see this text, would it try to spider the iframe content as a different url. I just don't want it showing up in results on it's own without the rest of the page.

You would treat the <iframe> element just as you would a <frameset> element. And yes, the src of the <iframe> will get indexed. But, if its an orphan page, the chances of that page having an effect on anything is slim to none.

Content between the <iframe>Content here</iframe> elements is what gets indexed by the bots. This is the same effect as if you were using the <noframes> element of a <frameset>. This is all part of the html guidelines and you should utilize these areas as suggested by those guidelines. ;)

16.5 Inline frames: the IFRAME element
[w3.org...]