Sexing a duck by bill freckles?

[KCNC06]

I know a duck's voice is the best way to determine gender in breeds where males and females look alike, like my white layers. But I have a duck that is recovering from suspected lead poisoning (won't go into that here though because I had another post going about that issue) and I don't think her voice has recovered completely yet. Two weeks ago she couldn't make any sounds. If she tried to talk or hiss, no noise came out. Her voice has been returning and she talks more every day but I'm not completely sure she sounds like a she. At the same time, I know she's still recovering and has neurological symptoms so I don't know if this is her "real" voice.
All that said, I'm curious if freckles on their bill always means it's a girl. I've read a few articles, including the Majestic Waterfowl article, about freckles and it sounds like all ducks with freckled bills are girls even though not all girls will get freckles. I have other ducks with freckled bills and I know they're girls. But I wasn't sure if I was reading/understanding correctly so hoped for clarification. Boys don't develop freckles on their bills right? I know the freckles are just melanin showing through from pigment going to yolks so it doesn't make sense that boys would get freckles. They shouldn't be losing pigment.
Here's picture of her freckles:

 

[Lacy Duckwing]

Hmm... I've never heard of a duck's freckles meaning that it's a girl, but it is interesting. I want to keep that in mind. . You probably know this because you have ducks, but does it have the curl above it's tail? The curl on certain breeds mean drake. Voice is your best bet, but as you said she lost her voice earlier. Time always tells when one lays an egg.

 

[KCNC06]

I think I saw this article linked on here before, but in case I'm wrong here's the link to the Majestic Waterfowl thing about freckles: http://www.majesticwaterfowl.org/ar...xing a Duck by Their,be either male or female.

Her voice sounds like a girl to me, it's just not as loud or squeaky as the girls I'm with all the time. She does sound very similar to my other outdoor girls though. She doesn't have a curled drake feather either but I don't think all of my drakes have them. And I know at least one female duck who has a curled tail feather. Phoebe is definitely old enough to be laying but obviously isn't right now.