Stephen,
 
We had the same couch troubles.  What we did was stapled a heavy duty
plastic (actually a waterbed mattress, but that's a whole different story)
to the bottom, and for the problem with the space between the cushions,
first we stuffed the space with plastic, then we we duct taped that area.
It doesn't prevent them from trying from time to time, but so far its been
100%.
 
- Mish
 
MICHELLE Z. MATTA.........Carnegie Mellon University
Athletic [log in to unmask]
http://www.contrib.andrew.cmu.edu/usr/mish/home.html
[Posted in FML issue 1476]