Certainly have run into that myself. On some larger projects, it certainly makes sense to scrap it and draw up an extensive design document, diagram the elements and re-develop. Especially since AS3 came along. It doesn't make sense to create a large project without doing this...unless, of course, the client comes to you with an unreasonable deadline, makes changes mid-project and makes development decisions that change how you code it...not that it would ever happen that way...

If they do let you re-code it, be sure to review this page:
http://www.freevbcode.com/ShowCode.Asp?ID=2547