It's hard to monitor debug information in games using standard approach, using Visual Studio debugger breakpoints, watches, etc. for example. This breaks game cycle, hides visual output and useful only for catching special conditions. Also some data, like enemy AI calculated path is hard to analizy in it's internal form. I formulate this problem in this post at gamedev.stackexchange.com. This incredible lecture by Bret Victor shows why instant feedback (in our case it's just instant debug) is important, you definetely shoul watch it. This lecture impressed me, and that's probably how I begin to think about visualizing debug information.
Using techniques described in post I can visualize objects information like this:
The cell coordinate for digger object is displayed above him, and moves with him.