Even i have seen this type of incidents in Kerala as they issue unreserved sleeper tickets there. Though people with general ticket enter the reserved coaches, TTE wont object as they tell that they will get down in next station and that will never happen. Adding to this, including Rajdhani, trains travelling in Kerala stops in all small stations also which makes the genuine passenger getting disturbed. I have seen cases where people board the train when it gives a technical stop though its not an official halt.