I've just got a crappy sound in Skype 188.8.131.52 on Ubuntu 13.10 (64-bit) and after some searches, has found a workaround here: http://community.skype.com/t5/Linux/4-2-0-11-1-for-linux-crashes-when-answering-calls/m-p/1655001/hi...
However, the solution which helped me on 64-bit system was the following:
1. Remove original sound plugins with the command: sudo apt-get remove libasound2-plugins
2. Reinstall them again without specifying the "i386": sudo apt-get install libasound2-plugins
Hopefully that will help someone else here as well.