How to troubleshoot code in a model?

[eluser]35mm[/eluser]
I haven't been able to echo anything from models? In the end I had to pass back a string to the controller and show it in the view, and move the string about until I found the fail point (which was a miss named var). Obviously being able to simply echo would be a lot easier! So how comes echoing from model doesn't work for me?

Thanks for the tips on unit testing and profiling!