Turns out the answer is 'very easily'. I tested by opening testpoints with dataviewer and dtt (aka diaggui). The have different behaviour, with dataviewer generally doing the right thing and dtt doing the wrong thing.

The tests are

1: open the application, open the testpoint, logout of the computer, log back in.

2: open the application, open the testpoint, power down the computer using the power button, power the computer back up, log back in

Dataviewer:

Test 1, once the user loged out, the testpoint was cleared. PASS

Test 2, after the machine was powered down, the test point was stuck on. FAIL. When the computer was powered back on and before the user logged back in, the test point was cleared. PASS?

DTT:

Test 1, after logout the testpoint was stuck on, had to manually clear it. FAIL

Test 2. after power down testpoint was stuck on (even though h1nds1's log showed an "about the clear' message). FAIL. After computer restarted test point still stuck on. FAIL.

So DTT users can easily leave stuck test points if they dont cleanly exit their dtt sessions before logging out or powering down.