Memcached common misuse is to use it as a data store, and not as a cache
Never use Memcached as the only source of the information you need to run your application. Data should always be available through another source as well
Memcached is just a key or value store and cannot perform query over the data or iterate over the contents to extract information
Memcached does not offer any form of security either in encryption or authentication
If you like this question & answer and want to contribute, then write your question & answer and email to freewebmentor[@]gmail.com. Your question and answer will appear on FreeWebMentor.com and help other developers.