Disadvantages

The main drawback of folksonomies that social bookmarkers use is that tag-based systems have no standard set of keywords and no controlled vocabulary. Hence, different users might tag a single item differently. A website about cars can be tagged by one as "cars" while another person may tag it as "automobiles." To be even more specific, a user can tag the item with the brand like “Lexus” or “Ford.” Then there are the differences in the structure, such as "cars" vs. "car," or "auto" vs. "automobile." Highly personalized tags may also be limiting, in that this might prove to be problematic especially when doing searches.

Further, there is no way by which keywords can be related with each other. For instance, taxonomy would dictate that "human" is classified under "mammal." As such, searches for keywords "mammal" are also likely to include humans. With folksonomy, however, each keyword or tag is held independent of others.

Also, folksonomy is prone to human error. For instance, misspellings are common in tag-based systems. The tag "cars" may be misspelled as "cras" and the system has no way of correcting this. The result would be that the link might not appear when other users search for the keyword "cars."

Another drawback of social bookmarking systems is the possibility of abuse, such as with "gaming" of the system. Since social bookmarkers and social news sites mostly rely on quantities of users voting or bookmarking an item to determine importance, there are ways by which this can be simulated. One is by using multiple "dummy" users bookmarking the same item. Another is by colluding with an insider--someone who has direct control over the system, and who can manipulate rankings. Another, though more difficult to execute, is through social engineering. Large groups of "friends" can be used to vote an item up in the hopes of influencing others to do the same.