I'll just archive this, the current Skype version for Windows that doesn't seem to have any ads.
This is a simple ad blocker for Skype. If you also got tired about "You are our 1.000.000th visitor!!1!" or "Doctors hate him!", this might be interesting for you.
Before:
After:
Just inject that dll into Skype.exe, and enjoy.
Please note this won't remove ads in the call screen, as well as on the start page. Also do note the ads get removed after resizing the window a little bit.