I’ve never had a problem with them myself.
Over the past few years I’ve been pulled into VOSA checkpoints 3 times and always found them to be polite and friendly.
The last time the wheeltappers went over the vehicle like they were hoping to find gold then let me go without checking my card, but even a 45 minute delay isn’t so bad if your being treated right, and being paid for it 
Sent from my mobile.