So, I too have tried all of the recommended methods (both lore and Internet varieties)...
And it's true, most do work to some degree... Just not completely.
That is to say, it's not until mid-fall when they seem to finally seem to be eradicated!
I believe the reason is that many that crawl through the holes in the plastic wrap, simply crawl back out.
I know, I know, many say they aren't that smart or they can't find the holes again but I say that's rubbish!
They got in through the holes, didn't they?
If you are using solid bait, or if they don't fall in the 'drink' if you are using a liquid like vinegar or juice, they may find their way back out... After all, they walk on walls and ceilings so if they found the hole while right side up, they can find it again while upside down!
Why do I think this one is better?
Well, it uses a liquid (in addition to or in lieu of) just a solid bait... But more importantly, it pumps liquid up from the base like a fountain, hitting the top and causing the liquud to run down the sides this flushing the critters into the drink... For ten seconds at a time, every ten minutes, every hour every day!
Neat! Even the ones that don't want to drink get to go for the eternal swim.
Then when it's time, just open it up, dump the spent bait liquid and all the dead flys down the drain, rinse and refill. Sweet!
Disclaimer: I don't personally know the inventor, just that he's local and did some testing at one of my local nano brewerys... And I think it's neat and I think it will work better than whats already been tried.
