Some SEOs have a big reputation because they have Fortune 500 clients. I call these firms White Collar SEOs. I mean no disrespect towards these SEOs when I say this, but I mean really, how hard would it be to optimize for a company that is so well-known that it comes with hundreds of thousands of backlinks built-in? And let's not forget the substantial budget you'd have to work with. The SEO work would most often focus on some simple on-page changes, or worst case, dealing with a badly seo'd dynamic site. Have a staff of trained underlings make these changes, and the mega-company will easily rank. Ok, let's back up a bit. These White Collar SEOs need to work hard at meeting with and pleasing the upper echelon of business society. They also need to have a good understanding of how best to spend those large budgets. They also have to be able to manage and run a business that involves employees. These are all things I would not be good at doing.
I consider myself to be a Blue Collar SEO. I work in the trenches with small sites that have no reputation to precede them, and no budget to speak of. I don't need a white button-down shirt or fancy suit because I don't have meetings with CEOs of large corporations. I don't need a PowerPoint presentation because I don't spend my time selling my services to a Board of Directors.
I wake up, sit down at my computer (still in my pajamas) and start my day. I consider my pajamas to be my blue-collar uniform. I don't have anyone working for me. I do all of the work myself from idea, concept, design, optimization and link building. This is the down and dirty trenches of SEO; taking an idea from start to finish with nothing but your own wit and work to guide you.
The final outcome will usually not create the massive sums of money that the Fortune 500 companies will make. Indeed, my income is much more typical of a Blue Collar income. It pays well. It pays the bills. It gives me enough to enjoy my life without financial stress and worry. In short, I am a happy, stress-free Blue Collar SEO.
If you are an individual working on your own site, with a very limited budget, you are also a Blue Collar SEO. If you sell your SEO services, mostly to individuals with one small site, you are probably still a Blue Collar SEO. If however, you have a decent sized staff and your clients have large, high-profile sites, you probably are a White Collar SEO. Both types are necessary. Both types require special skills. I think it would be interesting to have an informal meeting once in a while where White Collar SEOs met with Blue Collar SEOs to share ideas. I think each would learn a lot from the other.