IDG Contributor Network: The 3 worst on-site ad fails

Advertising messages form an essential part of an effective online strategy for a website. They can generate revenue, increase conversions and grow mailing lists.
They have evolved from static banners restricted to sidebars to dynamically served content that can make or break a visitor's experience. From interstitial ads to pop-up messages to scroll boxes, ads are being used in an ever-greater capacity to drive results on websites.
Yet many businesses are using ads in ways that hinder, rather t