The good news is that search engines have figured this out, and are now on guard for "spam" pages and sites that have increased their rankings by artificial methods. When a search engines tracks down such a site, that site is demoted in ranking or completely removed from the search engine's index.
The bad news is that some high quality, completely above-board sites are being mistaken for these web page criminals. Your page may be in danger of being caught up in the "spam" net and tossed from a search engine's index, even though you have done nothing to deserve such harsh treatment. But there are things you can do - and things you should be sure NOT to do - which will prevent this kind of misperception.