For website owners, Blacklisting means your website is removed from the search engine(s) index. Which means that even if someone searches for your website, it won’t show up in the search results.
If you have a typical website that gets 75% or more of its traffic from natural search results, getting blacklisted is a death sentence. For that reason search engines don’t want to blacklist websites carelessly. They take it just as seriously as you do. That’s why its not easy to get blacklisted.
There are only a few ways you will get blacklisted. Usually its results from employing blatant tricks on the search engines – something you really have to work at. So the assumption is, if you do get caught playing a trick on a search engine, you deserved it.
So is there a reason to worry? No. Not for the average person/business/website. But you should be aware that some third party services you “could” employ to promote your website, could expose you to such risk.
Some SEO services are willing to walk that fine line between whitehat SEO (acceptable) and blackhat (bad) SEO practices. Therefore its important to know exactly what your SEO vendor will do to promote your website – before you engage them. Unfortunately SEO services are often considered proprietary art. This type of SEO firm will often tell you flat-out “its proprietary. We don’t want our competition to know how we do things.” There are several reasons why an answer like that is a signal to not hire the firm or individual.
But simply, SEO is not a secret dark-art. SEO is doing a lot of things well – some are really hard to do well, while others are simple (and often boring). You should not be afraid to demand explicit answers to your direct questions. If an SEO firm will not tell you how they do “their thing”, go elsewhere. The old-timers in SEO will tell you there is nothing proprietary about it. Its just hard work. Wrapping it in proprietary BS means they are hiding something; incompetence or blackhat seo. Either way…as they say, “you have been warned!”
Learn a bit about Black-hat SEO and ask questions. There are some very reputable SEOs out there. Unfortunately the way marketing tends to work, you tend to be bombarded by pitches from those SEOs who are not too busy.