I can't speak for other jurisdictions, obviously. In Georgia,
"petitions for initiation, advancement, affiliation and dimit require unanimous secret ballot"; only the Master's proficiency
may be voted openly, and lodge bylaws or Master's decree may require that to be secret ballot as well. Naturally, your open vote is observable by all present.
Excerpts from the 2005 Georgia Masonic Code (latest soft copy I have):
41-112. Secrecy. —It is exceedingly improper and un-Masonic for any brother to make any remark, reflecting upon the ballot of any other brother or the motives influencing him. The ballot is and should remain secret. No brother has the right to inquire who cast a negative ballot or why. No one has the right to say how he voted, or why, and a by-law contravening this is void...
41-116. Vote Required.—Petitions for initiation, advancement, affiliation and dimit require unanimous secret ballot...
As far as what criteria are generally used to determine proficiency... we have none. Each brother present must decide for himself if he feels the candidate should advance or not.