Clique-Percolation Algorithm's "corner cases"
Finally, I've found that the answer is that exists the possibility of leaving out many nodes out of any resulting community. There isn't any specified way in the original CPM algorithm to deal with them.

For anyone interested on a possible way to handle the left out nodes, there is an interesting article explaining an extension of CPM to do that:


Extended Clique percolation method to detect overlapping community structure : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6968420&amp;pageNumber%3D33268%26rowsPerPage%3D100


It seems that the modularity score obtained with this extension is usually better than the produced by the original CPM, but it comes with a price: it's slower.