The digital probe thermometer is actually the one that's more likely to be accurate and the dial is the one that's more likely to be off. And you always want to measure exactly where they bask if at all possible, because the temperature can be quite a bit different only a few inches away from right under the light bulb. My reptiles have demonstrated that to me by moving their thermometers around :wink:
There seem to be lots of adult bearded dragons that aren't too good about eating their veggies, and only want bugs, and many of them seem to manage to stay reasonably healthy anyway, ours included. So don't stress out too much if you can't get yours to do the recommended 80% veggie diet -- you may have to settle for whatever percentage you can get :roll:
Bearded dragons are very good at holding out for their favorites until their human slaves give in and feed them what they want, and when it comes right down to it I'd rather let them eat a diet that's not quite what's recommended by the so called experts, rather than let them go hungry. But that's just me, and I should disclose that I'm pretty much a total failure when it comes to "tough love"