With so much talk going on right now regarding google and their changing of the guard regarding serps and what we do to increase our likelyhood of ranking high, how can seo companies claim to boost your ranking if we do not even know right now what factors will help us... Example paid linking, link exchanges and so on now having minimal weight.
As with any other business, there are cons in SEO world as well. You should always check their previous work and talk to old clients before hiring anyone.
that's just the point, a company's previous work means absolutely nothing, if that company is continuing to use techniques that we now know are frowned upon.
I think seo companies should try an experiment to know if what factors affect rankings. We all know that google won't reveal their secret that's why they always change their algo.
SEO companies can't promise top rankings. Website rankings rely on a 3rd party and the ever-changing algorithm. SEO companies can only promise to apply practices that have brought results to the other clients of the SEO company. It is always a good idea to do a little research on a company before hiring them. If they use techniques that are now frowned upon then their past clients shouldn't be ranking that well anymore.
"You" may not know what factors help and what doesn't, however a good SEO does. Example, i've got just over 50 websites and primarily use a single different technique and approach on each one and a combination of techniques on others. I track their rankings daily and by monitoring their SERP's over time it produces a trend on what factors are loosing momentum and what's gaining momentum. This enables me to launch a site, or optimize a clients site using techniques i know work.
Seos are different and believe it or not A good SEO will always be able to achieve great results, for example there is something called viral marketing (link baiting) and personally i'll not buy one single link, what i do is create a special quality and related content for my clients websites, i wont give much details but this content will get thousands of natural links, this iw way better than getting in the Digg home page for example.., after that there is no way your rankings doesnt rocket because you become the authority in your niche... however very few Seo's have my approach to link building.. so just make sure u choose the right company.
Good question and those that rely solely on link exchanges or buying links could suffer. I think as always that having good content optimized with relevant keywords will be the best way forward.