Well, yes, I would say it's rude if you have no reason to say no. At least hear them out is usually considered nice.
But...
If the person is clearly wanting to sell something to me, or trick me into something, or take advantage of me (typical in touristic places) I would just say "no thanks" and move on.
Spotizerr + navidrome + tempo
Spotizerr (fast development, sometimes breaks) will let you download you spotofy playlist. 320kbps too if you have premium. Also, deezer premium accounts are free for 1 month and let you download flac.
Navidrome replace Spotify as streaming server.
Tempo is a good android client. O also love symfonium but its not free (very worth paying for, though).