Should I use Libraries API if I only wish to use a 3rd-party library for my own custom module? version detection, duplicate declaration
I think the answer would be to check for an API module that wraps the 3rd-party code inside a Drupal module, in my case this would be the Flickr API module, which has been fixed to use Libraries API:

https://www.drupal.org/node/2301991

If there isn't a wrapper for the 3rd-party code, then this would be the case to make one, by oneself.