You can just see how this will go
Anyone who is any good (lets call them "Bob") will tell them to get stuffed and get another job pretty quickly.
The remainder of people will fall back on one or more of the following:
1) I didn't work on that part of the system
2) Bob wrote that, I'm not sure how it works
3) That code was written after I left
4) That's not my code
5) I wrote that but it's since been updated by the outsourcers.
6) That's a feature.
7) Yes, I can look at the problem. I can give you a day in three weeks time