I used a pressure bleeder for many years. The better ones have a rubber diaphragm between the fluid and the air, so they can't mix. One precaution, the fluid can absorb moisture if it's left in the bleeder ball, so don't get in the habit of leaving the ball filled between brake jobs. "Wet" brake fluid has a much lower boiling point than fluid that's been kept away from humidity.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!