That being said, there are accents of Standard Swedish in which it's quite common, but the key here lies in the very first sentence of this post: regional, it's not a sound that you'll hear on national news, and barely even on regional news in the areas where normal people use this sound. I also think Norrland is the only macro region where you can speak Standard Swedish in everything but prosody and exact pronunciation of the usual phonemes and still have thick l, around here only those who speak full-blown dialect or retain quite a lot of it in their everyday Swedish have both l sounds, but then you use non-standard vocabulary, grammar and a phonology that plays completely by its own rules too, not just an extra allophone of /l/.
Anyway, I made a recording of a few words with both sounds so that you can compare them

https://www.dropbox.com/s/75pl5f6b7mseh ... l.mp3?dl=0
bli, valv, älg, stol
Edit: I'll also try to find something in the local dialect that I can record so you can hear the sound in a bit more natural setting, recording individual words without exaggerating things is hard
