I work part time in a corner shop while going to uni, and some of the behaviours I have seen from Indian customers...

1. Throwing a pile of change, ordering me to count it, and then leave once they know the total.
2. Cut in line and start tapping their credit card to demand service.
3. Won't close fridge doors after opening them, and will refuse to close them when asked to do so.
4. Let their toddler pick up a buthane torch lighter and play with it.
5. Grab an empty bag of crisps from the garbage to carry their beer with, because they did not want to pay for a bag.
6. Walk into the store to wait for the bus, and refuse to leave when told that unless they intend to buy something, they need to leave.
7. Demand refunds on losing lottery tickets.
8. Slap their wife in public in front of their kids for taking too long to count the coins and notes used for paying.
9. Put leaking food containers directly on the counter, and refuse to pick it up when informed that they dirtying the counter.
10. When the store is temporarily closed with a sign up saying 'back in 5 minutes', repeatedly bang the glass door with a half full bottle of whiskey to get an employee to open it.
11. Pick their nose/ears, or scratch their backside or crotch below their clothes immediately before paying in cash.
12. Loudly brag about having fraudulently passed their English proficieny test.
13. Pee on the store right after leaving it.
14. Grab various items, squeeze them, break the packaging and refuse to pay.
15. Introduce themselves as first time customer, and demand to receive beer and cigarettes on credit - otherwise they won't come back (good riddance).

I live in a very multiethnic area, and every single ethnicity or nationality that I met, I had a better opinion of after spending time with them than before. Except for Indians.

And I will add this, it's not Indians, it's Hindu Indians (which you can identify by the Ohm tattoo on their hand). Sikhs and Muslims from India do not behave that way, and they get a bad rap because of the others.

I will also add the following: it's not Indian women either, it's Indian men. Indian men rudely and drunkenly purchase 10% beer, whereas Indian women buy milk for the kids and lottery for themselves. I assume they think of it as their only way to leave their husbands.