Bollywood songs are terrible in my opinion, they delude impressionable young girls into living a real life bollywood love stories.
I've noticed that people, after listening to these type of songs want to immitate what they've seen/heard on the screen, and the majority of the time, what they've heard/seen isn't halal.
There was 1 girl in my college, and she had a BF and she would all ways relate her life back to bollywood lol, whenever something would happen between her and her bf, she would go, " we're like sharukh and kajol in such a such movie"
and my male friends would use the lines from these bollywood movies on girls, and the girls would fall for the lines. Aferwards my friends would laugh at their stupidity for beliving a word they said.
All in all I think bollywood is a very bad influence, especially on young people, they put a desire in people to achieve a certain thing, mainly a real life romance similar to the one seen on the screen.
Is it even halal to watch these movies where non mehrams are acting out haraam scenarios with each other? and women walking around uncovered as well as men exposing their bodies.
then what about listening to the filthy music that they create from these movies with lines such as, "I love you more than my god"
more examples can be seen here,
http://www.youtube.com/watch?v=hKjvoGWZ2tA
@ the OP, I think in modern times the hijaab or beard are no longer a sign of piety, it's quite possible that people who adorn themselves in the muslim dress code do not possesse the piety that their dress promotes.
So I don't expect much in terms of piety from a girl in hijaab or a guy with a beard, I take everyone as an individual now. Hijaab or beard are no guarantee for a good righteous person even though we equate the two with a good righteous person.
also, Yasir Qadhi on how Music affects the heart.
http://www.youtube.com/watch?v=CMAmKYc4DHY&feature=related