When you are working towards a specific goal esp. if it is a looming mile stone or something to that effect, you tend to leave stuff behind, cut some corners, just a wee bit of slack... This "stuff" has a nice metaphor to describe it. It is called "Technical Debt" .

If you don't mind your technical debt it can grow so much you'd end up with a big-ball-of-mud which is hard to maintain, change and, well, do anything useful with.

The best way, I've found to deal with this is to "add a card" every time I feel the urge to add a //TODO comment. Or in other words add the technical debt as a task into the product/task backlog.
Having the technical debt on the backlog has several benefits such as

• It will not be forgotten - it will be documented...
  
• It will not be hidden - The true state of the product will be in the open for management/product owner to see. As a manager I want to know the true state of the product. If I know what I can and can't have I can get ready for that. If I think everything is rosy and then the system blows up in my face, that's not so good..
• It will be managed - The importance/relevance of the "debt" will be reevaluated every time the product backlog get prioritized.
  

Technical debt will occur in your project, whether it is agile, "water-falled" , incremental or what not. Don't ignore it