On the subject of Brasses: 1811 Dictionary of the Vulgar Tongue (please note that the link may not be entirely safe if your boss is at your shoulder.) gives this definition for 'Corinthian'

Corinthians. Frequenters of brothels. Also an impudent, brazen faced fellow, perhaps from the Corinthian brass.

(I found that by searching the dictionary for 'Brass') Which sent me off on a small journey of discovery to see what Corinthian brass was and if it had any obvious link to prostitution. It looks as though the corinthian reference is twofold. One aspect is that they customers were literally 'brazen' the other is that(according to the MacArthur New Testament Commentary)

Corinth was such an immoral city that its name bcame a byword for sexual vice; the verb to ‘Corinthianize’ meant to commit sexual immorality, and ‘corinthian girl' became a slang term for a prostitute.

So my speculation is that the phrases 'Corinth Girl' and 'Corinth Brass' met up in the brothels, became confused and we ended up with the meaning of one attached to the other.

On the subject of Brasses: 1811 Dictionary of the Vulgar Tongue (please note that the link may not be entirely safe if your boss is at your shoulder.) gives this definition for 'Corinthian'

Corinthians. Frequenters of brothels. Also an impudent, brazen faced fellow, perhaps from the Corinthian brass.

(I found that by searching the dictionary for 'Brass') Which sent me off on a small journey of discovery to see what Corinthian brass was and if it had any obvious link to prostitution. It looks as though the corinthian reference is twofold. One aspect is that the customers were figuratively 'brazen' the other is that(according to the MacArthur New Testament Commentary)

Corinth was such an immoral city that its name became a byword for sexual vice; the verb to ‘Corinthianize’ meant to commit sexual immorality, and ‘corinthian girl' became a slang term for a prostitute.

So my speculation is that the phrases 'Corinthian Girl' and 'Corinthian Brass' met up in the brothels, became confused and we ended up with the meaning of one attached to the other.

On the subject of Brasses: 1811 Dictionary of the Vulgar Tongue (please note that the link may not be entirely safe if your boss is at your shoulder.) gives this definition for 'Corinthian'

Corinthians. Frequenters of brothels. Also an impudent, brazen faced fellow, perhaps from the Corinthian brass.

(I found that by searching the dictionary for 'Brass') Which sent me off on a small journey of discovery to see what Corinthian brass was and if it had any obvious link to prostitution. It looks as though the corinthian reference is twofold. One aspect is that they customers were literally 'brazen' the other is that(according to the MacArthur New Testament Commentary)

Corinth was such an immoral city that its name bcame a byword for sexual vice; the verb to ‘Corinthianize’ meant to commit sexual immorality, and ‘corinthian girl' became a slang term for a prostitute.

So my speculation is that the phrases 'Corinth Girl' and 'Corinth Brass' became confused and we ended up with the meaning of one attached to the other.

On the subject of Brasses: 1811 Dictionary of the Vulgar Tongue (please note that the link may not be entirely safe if your boss is at your shoulder.) gives this definition for 'Corinthian'

Corinthians. Frequenters of brothels. Also an impudent, brazen faced fellow, perhaps from the Corinthian brass.

(I found that by searching the dictionary for 'Brass') Which sent me off on a small journey of discovery to see what Corinthian brass was and if it had any obvious link to prostitution. It looks as though the corinthian reference is twofold. One aspect is that they customers were literally 'brazen' the other is that(according to the MacArthur New Testament Commentary)

Corinth was such an immoral city that its name bcame a byword for sexual vice; the verb to ‘Corinthianize’ meant to commit sexual immorality, and ‘corinthian girl' became a slang term for a prostitute.

So my speculation is that the phrases 'Corinth Girl' and 'Corinth Brass' met up in the brothels, became confused and we ended up with the meaning of one attached to the other.