Maybe your experiences are different but from my friends and personal experiences it happens all the time. Two brahmin friend of mine who were looking to rent in a posh locality in Bangalore had to provide their contacts in the village to make it clear to the landlords that they were genuine brahmins from the right caste. Incidentally, both were PhDs from US institutes so that did not prevent the checks. Remember, Bangalore is a reasonably progressive city. Caste checks are routine and frequent in smaller towns and villages.