Wudhu

Making wudhu with nail polish

Q: Why is wudhu not valid if someone wears nail polish? Wudhu is a matter of cleanliness, so if anyone wears it after cleaning their nails then the dirt will only touch the nail polish. When performing wudhu, the nail polish will be washed. So why should the water should reach the nail? 

Experiencing a slight discharge after thinking about something

Q: I would like to know if ghusl is fardh on a woman if she has a thought and feels a slight discharge, but doesn't check it because on every ocassion it is seen to be normal discharge, and not mani.

I always experience this during istinja and have checked on many ocassions, but have recently stopped checking because I experience a lot of normal discharge and know it can't be mani. I am still doubtful. Am I ritually impure for not checking this time?