pursuit

I wonder if anyone has any experience of dealing/using one of these so called seo companies. for me, I always tend to take take it with a pinch of salt about claims of making a site to appear at top of google search results made by these companies.

The reason I have my very doubt on this so called seo 'service' is based on this scenario:

say I present myself as seo guru. there are scroes of online shops selling the same products. Igo to site A offering my seo service claiming to be able to make siteA at top of google search. I then also go to site B, which is of course a competitor of site A , C - Z, and offering same service and making same claim. Now, isnt there a logic flaw in all thes claims: google can only list sites from top to bottom and from page 1 to page X. So at the end of the day, there has to be sites, either site A or B --- or Z, all of whom use my seo service, got to be at the bottom. there is no way to list site horizontally so that everyone seems to be a winner, or unless you list all sites in a circle so that there is no beginning or end, ie, no first and no last.