@Precious Star: I've asked imaams, ullamas, ustaads, maulanas, etc about this kind of thing. Majority of them have told me that for a positive sign you may experience a good feeling developing inside you after making dua or you may have a positive dream (including seeing white or green colours) or both; for a negative sign you may experience a bad feeling inside after making dua or you have a bad dream (including seeing black or red colours) or both; for neither positive nor negative you may not necessarily get any feeling at all nor a dream in which case you do whatever your heart feels more inclined towards, i.e. going for it or not. I've also looked into Islamic dream interpretations, most famous Ibn Sireen, who's work is based heavily on Hadith. He describes a lot of dreams in great detail whether they are good or bad interpretations.
@Aapa: It's a general question. Sometimes mothers won't bother praying Istikhara because they may choose to rely purely on their instincts/intuition and say that if the Istikhara was good for you then she would be for it instead of against it. On top of that, she may not give any valid Islamic reasons why something is NOT good for you even though Istikhara results are positive for you. I understand that Allah (SWT) says in the Quran that we should respect and obey our parents, however He also says that something that we dislike might be good for us while something that we like might not be good for us and Allah (SWT) is All-Knowing, All-Wise.
I hope I don't sound too naive/ignorant as I am learning more and more about various things in our deen on a daily basis and everyone has their own views and opinions. I didn't even know about the different types of Sunnis until last year, like there are Wahabis, Salafis, Berelvis, Deobandis, etc :S .
I appreciate it.