I've done it twice before on QF international flights when priority boarding was not in operation, making it very clear to the person at the gate that I was looking for the priority boarding lane. I did feel uncomfortable, but it could be the difference between another glass of champagne before take-off, so one must have one's priorities in order
Domestically I wouldn't do it - especially out of CBR when 3/4ths of the flight are probably entitled to it
Oh, and dirty looks - you still get them when using official priority boarding anyway. I had the biggest death glare from a pleb on American Airlines once when using priority boarding. I was called forward and a guy from the pleb line pushed in front - gate AAngel's response to him: "Sir, you'll need to step back right now" before charmingly turning to me and welcoming me
The glare continued when he passed me getting comfortable in First.
-Shaun