You're right.

Never seen that Tettra dot. Everybody at the field calls the Dubro fill valve a fuel dot.

When I was told about them a couple of years ago, I swung by the LHS on the way home from the flying field and asked for a fuel dot. The hobby shop owner walked over to the wall and pulled down the Dubro valve without saying a word.

I'd say the consensus at the field is that they're not dependable.

If you look closely at the picture of my P47, you can see what I call plugs. Tower sells 'em and you know what Tower call's 'em? http://www3.towerhobbies.com/cgi-bin...&I=LXK138&P=ML

So it looks like nobody is on the same page.