That's what I'm referring to "ale laska" started out near polskie bloki, any time a sluttier, skankier dressed girl walked by... not necessarily pretty.
The part where you state where the word started is certainly not true. The rest, if based on the first part may be pretty dubious too.
"Laska" in Polish and in reference to a girl was coined sometime in the late 1960's and became mainstream in mid 1970's after a Polish comedy performer (forgot the name - Andrzej Rosiewicz?) sang a parody of a song from a 1964 Czech movie under the title Láska nebeská
(Heavenly Love). So "laska" in colloquial Polish came to mean "love" or a pretty girl. There were no negative connotations at the time.
The word laska also meant a cane/walking stick and indeed, it was used in street Polish to denote penis. Slang changes very fast so I can't vouch for the innocence of the word "laska" in Poland today, but to the ears of those Poles I know, though still colloquial, it is certainly not impolite. As a matter of fact my wife, whom I never heard say the most popular Polish word (kurwa) has no problem with using this word. I'm not even sure I heard her say dupa at all. (dupa is a very mild word). If she uses a word, Polish or English, then the word is boringly deprived of any spice, but not necessarily of humor.
There is also an adjective created from "laska" - laskowata/laskowaty, i.e. slangish for pretty/attractive and we use it at home pretty much on a regular basis. Jokingly, we will describe a car as "laskowaty".
But again, I haven't lived in Poland in a long while.