Tehillim 107:40 endorses the practice of plying potential donors with alcohol when it says
שֹׁפֵךְ בּוּז, עַל-נְדִיבִים
but we see from this question that mixed drinks are forbidden under any circumstance and we can only serve straight liquor.
I was wondering if a heter exists to use cocktails specifically in the case of parting rich people from their tzedaka money in light of the Mishna (Avos 4:15) which says
הוה זנב לאריות
since lions are always used as a symbol of power and wealth.
We say in al hanisim
ושללם לבוז
And for the purposes of taking spoils, use booze.
Thus it is permitted to use cocktails in order to part rich people from their money.
When I attend parlor meetings (Tzedaka events usually in someone's home) sponsored by rich Orthodox Jews, I hardly ever see mixed drinks. Logistically, they're not hiring a bar-tender to make the drinks for you. (No offense to frum Jews, but, few Jews know how to make a proper margarita.)
Most of them are serving single malts (aka very exquisite expensive whiskey. Many brands costing in the $100+ range per bottle).
There's a verse that supports this idea from Tehillim 123:4
הבוז לגאי יונים
The booze is for gay doves.
Too much booze turns people into happy uncontrollable birds whose heads are in the clouds, flying off or into the walls. Mixed drinks are the worst because they have more than one type of booze mixed together. You don't know how much of each type is in your drink or which drink is making you fly.
So, in general, it's not a good idea to have any booze. But, at a tzedaka event, you do want people to loosen up a bit so that they don't become a tightwad and don't donate anything. But you want to limit them to just one good drink. That's why the hosts serve single malts.
You have misunderstood the question you linked; not only are mixed drinks permitted, but several of them are mentioned in the Tanach. Mixed drinks are fine so long as they are not combined with dancing.
That said, there is a practical reason not to serve mixed drinks at these kinds of events. Your stated goal is to ply rich people with alcohol in order to separate them from their tzedakah money. Rich people are busy people and time is money, so you want to do this as efficiently as possible to avoid causing them a loss. Mixed drinks are inefficient because they are less concentrated -- the "mix" is stuff other than alcohol, like fruit juice or seltzer. Your donors will have to drink more rum & Cokes to get to the same level of enlightenment that a single shot of Scotch can achieve. (Source: I'm a moderator on Beer, Wine, & Spirits.)
To best serve your tzedakah goals while being considerate of your donors, serve straight liquor so they can quickly understand your needs and give over their tzedakah.
Mixed drinks are considered along with mixed dancing. Mixed dancing is not allowed, there must be a mechitzah. For mixed drinks similarly there must be a divider at least 40 ml high. Bloody Mary's on one side, Johnny Walker on the other side. Not allowed to mix.
