Sadly, many business owners have been approached by less-than-ethical marketing vendors who promise SEO services but mainly deliver nothing. If you are paying $49/month for a service that promises you top rankings in Google, it is almost certainly a scam.
On the other hand, if you spend $1'499/month on SEO services, and they've never once talked to you about a content strategy or your target audience, chances are it's a scam too.
Unfortunately, there are many companies that still make a living spamming sites with your links. While you can see a quick uptick in rankings, the traffic is usually not qualitative. To top it off, if the sites that are linking to your site are deemed to be spammers by Google, you'll see your results tank in no time.
Many SEO companies do not have the skill set to build your brand the right way. They rely on automation software to execute a series of tasks. This means that by the time you realize that it may not be working for you, the damage will be done and you'll need to spend time disavowing spammy links.
SEO done right, however, increases brand awareness and boosts conversions with less expenditure of time and effort.
SEO done right, allows you to carve out a niche unique to your company and bypass the competition.