The trace tool in inkscape works best with a decent quality and clear image (it's no good for jpegs unless it is a very large image) and I'll only use it when the results are good.
The image I used in that tutorial was just about good enough, I tested it first to make sure. There was a little loss of clarity to the text. If I wanted to I could have made fresh shapes for the badge, reshaped all the letters or done the text from fresh (I don't find inkscape is good for arched text). But I just wanted to show the basics.