I've worked in SEO for 6 years (I'm an SEO copywriter), and I know there's good and bad in the industry, as in any industry. In SEO, I think the biggest problem is a lack of respect for the audience. That's why you get sites with poor usability, as described by throwaway123 below. But it's not always the SEOs who are responsible for that. Remember, they're being paid by someone. Yes, there are times when the SEO's client DOESN'T understand the impact of the SEO they're commissioning. But there are also times when they do. It's easy to blame the practitioners here, and often that blame is justified. But we only have to look around us to remember that business -- big or small -- is generally far more interested in short term gain than long term customer satisfaction. So it should come as no surprise that many businesses are prepared to turn a blind eye to practices that hinder usability and visitor value.
The other common problem in SEO is ineptitude. Many people call themselves SEOs when really they're just opportunistic freelancers and entrepreneurs. Their SEO knowledge is poor and their business management skills lacking. This ultimately impacts EVERYONE connected with the job, even those only remotely connected (like the good SEOs out there).
GREAT reply, patio11. It's not just a question of good versus bad SEO. Within each 'colour', there's a vast range of techniques. Not everyone knows about them, and certainly not everyone can implement them. More importantly, the things that really sets a talented ethical SEO apart from an inept ethical one are creativity and business smarts. Just like any marketing campaign, an effective, sustainable SEO campaign requires a deep understanding of the client's business needs and market.
The other common problem in SEO is ineptitude. Many people call themselves SEOs when really they're just opportunistic freelancers and entrepreneurs. Their SEO knowledge is poor and their business management skills lacking. This ultimately impacts EVERYONE connected with the job, even those only remotely connected (like the good SEOs out there).