1 and 2. getting drugged in a strip club, come on. It happened to someone, as I heard (a tourist spent thousands of PLN in a club and couldn’t remember how it happened), yes, but it does not mean that every time you are asked “hey come for a drink to our club” they intend to drug you and scam you for thousands of zlotys. Most of these strip clubs probably work like every other strip club, they don’t want any involvement with media or the police, so they probably don’t use nasty tricks like drugs on their customers, and being nagged by a half naked girl in a strip club you entered on your own will is hardly a scam, you asked for it and at this point you probably enjoy it.

3. Just check reviews of the place you plan to eat/drink in on the internet, problem solved. Everyone does it these days, you would have to look really hard to find a place that does not care about its ratings and treats foreigners like that. This might have been viable in the past, but not now.

4. Totally! Especially now that taxi drivers have competition, so they are more inclined on getting money. Never take a taxi that is already there, parked at the airport, central railway station etc. This is also the case for us locals, and we have a quick fix for this. If you don’t want an uber or bolt, taxis are a good choice, but only if you call a proper taxi company (even if there is a taxi from this company parked just next to you), something about how the fare is registered via the dispatch system vs how they might try not to register you as customer when you approach them on the street.

5 (4.) – you have a second “4.” in the article. Just use a respected exchange, and avoid ones around the main square that don’t have good reviews, again google is your friend. I think nowadays it is harder to get scammed like this exchanges rely on their reviews, too.

Now for the stuff you omitted, other scams:
– People will approach you and give you something for free (usually perfumes), they will say it is for you, a special sample that they are just testing, from this new perfume shop that will be opening soon, initiate a small talk, walk with you for a bit, and later use numerous social techniques to make you pay for it (making you feel like you owe them something, like you “won” a discount on the perfumes etc). The perfumes are usually Turkish knock offs worth maybe 10-15 PLN.
– A girl with a cut purse will approach saying “help, they stole all my money!” asking for some change for the last bus home. She does it every other day with the same purse.
– A kid may play accordion in a tram , and later use the fact that you can’t move away to nag every passenger about money. Please don’t give them money, they are not poor.
– A man or a woman may act like they are disabled, and ask for money (how to spot genuine person in need vs scam: scammers are usually younger, attempt to make a visible hint to their disability – violently shaking hands, extremely disfigured posture/walk, and often they cover their faces. Don’t give them money.
– Someone will approach you vouching for blind/deaf children, asking you to sign a fake petition. After he gets your involvement, he will ask you to donate money. If this is about disabled children and they ask you to perform actions before asking you to pay, it is probably a scam.
– A lady with a basket of roses scam, my favourite, and quite innocent. Also quite intriguing, because apparently restaurants themselves are sometimes involved (allowing these ladies in). Anyways, when you are on a date with a girl, and you are sitting with her at a cafe or a restaurant garden, you may be approached by a beautiful young girl with a basket of roses, who will smile and give your partner a flower either without saying anything, or saying stuff like “a beautiful rose for a beautiful lady” counting on getting reactions like “thank you!! omg this is so amazing! I love it!”. She might even ask your partner if she likes the flower. After a minute (after trying other tables) she will approach you saying you need to pay like twice the regular rose price for the flower, or she will have to take it back (making it look like you will be taking back this beautiful flower from the girl you are dating). To fight this you can just both say “no, thank you” as she tries to slip the flower in.
– Someone will ask you to buy food, because it is cold and they are poor, standing in front of a low quality restaurant. They will say “I don’t want money, look I’m not faking, here buy me a meal there, I would ask for money if it were a scam”. If you agree, it turns out the place only accepts cash. After you order a hot meal (usually chosen by the person) and pay, the cashier will try to keep the receipt for themselves to make a refund later (I’m sure they can deal with it even if you take the receipt though), and split the money they got between him and the person that brought you in after you leave. Because you wuldn’t wait for 30 mins to see the meal delivered to the table would you? Be aware that there are places in Kraków that give food to the homeless for free, and there are social support programs so no one should be hungry. If you really want to buy someone food buy it at the place of your choice, keep the receipt or just wait to see if they eat it.

To sum up, you only listed some of the problems, most of them are outdated. Also, recently it seems scam approach shifted from more detectable direct and aggressive approach (that may backfire on the scammer), to nuanced approaches playing on your feelings, that often fly under the radar – even years after the scam you can’t genuinely tell if you have been scammed or just helped someone in need.