Using an IFRAME for a simple advertisment. Is it bad for SEO?

If you look here you will see an ad that is intended to be embedded in another site as an advertisement. Here is an example of where it is embedded.

The code responsible for displaying the ad in the web site is this:

<iframe src="http://ads.lockedonmedia.com/zones/204" frameBorder="0" scrolling="no" style="width: 160px; height: 600px;">

I like t开发者_高级运维his approach in that, if the advertisement include dynamic content, such as "today's price," the content will be easily reflected in the hosting web page.

My question is this:

I realize that IFRAMEs present navigational issues, but is there a real impact on SEO and should SEO-sensitive developers avoid using it at all costs or are there circumstances where it can be used w/o harming your ranking?

One thing to keep in mind with using an Iframe for advertisements, never ever ever embed a raw location into it! If you use an Iframe pointing to a URL as your ad source at some point your website will become an attack site for serving malware from a nefarious advertiser that changes their legitimate advertisement to a malicious one.