The world of Search Engine Optimization has grown so quickly that it has enabled less than reputable firms to try and "cash in" on it's widespread interest. Google itself even references this notion in their Webmaster Central comments on SEO. Some of the most common instances of this I have found include the following scenarios:
1) Guaranteed First Page Results: No one can guarantee first page rankings, Google itself says so but what some companies will do is play the semantics of this and attempt to get your business ranked for terms that are not frequently searched and have a large amount of keywords, such as Search Engine Optimization Firms in Mount Laurel NJ which is obviously not searched all that often. Make certain to clarify how the keyword selection process will be handled. Make certain that you have a solid understanding as to what keywords the firm is actually attempting to have you rank well for.
2) Firms Referencing They Have Relationships with Google: We often hear of Search Engine Optimization Companies that claim to have a "special relationship" with Google that enables them to do things such as post their clients directly to the Google platform. Nothing could be further from the truth. Google offers no sort of special relationship to receive increased rankings but rather require websites to meet a large amount of specific criteria to gain high natural search results. The notion of "special relationships" should be considered a major red flag.
3) Automated Platforms which Directly Feed Google Information: The idea of any sort of automated software or platform working with providing Google with information is again a major concern. There are no short cuts in obtaining high natural search results, it is a process that is time consuming but will yield great results when actually done correctly. All of our work in done "manually" and while it can be rather laborious at times, the fact remains that is a very good use of time.
4) Outsourcing Services Overseas Helps Save You Money: While there is something to be said that overseas firms can offer services at a lower cost the reality of it is that the quality of the work is always poor and the end result is that you won't see the type of results you are looking for. Be very wary of firms that outsource their services overseas, it is something that should be clarified with them early on.
5) Different Plan Levels: The notion of the Gold, Silver and Bronze plans that some SEO firms offer is something that confuses me. Does a bronze plan only get you certain results? SEO is not a one-size fits all situation. Each customer is unique in what it specifically needs. Some clients need more of one thing and less of another. Don't be fooled by the different plan levels, any reputable firm needs to customize a program that will meet your website's needs.
As in choosing any type of vendor to work with, always ask for references and make sure you have the ability to "opt-out" if the vendor is not providing the type of quality work you would like them to. We work with a month to month program which we feel makes us accountable for our work and we live by the notion "what have you done for me lately"!