How does Guaranteed Page 1 seo services?

[Jake]

"How do those services do it"?

They really can't guarantee page for any search, typically they will sell a naive site owner on the value of ranking for their own site name, which if unique can be one of the easiest searches to rank for, but is also of very limited value. Some keywords may be 1 million times harder to rank for than others. Don't expect them to be able to get you on page 1 for valuable terms like "Weight Loss" or "Credit Report"

There are estimation methods that SEOs can use to to determine the time and investment ranking may take. A massive, long term site development campaign may be need to get ranking for important keywords.