Non-Resident Indians (NRIs) allege that a ring of unscrupulous immigration, customs, police and Air-India personnel at Indian airports are tampering with passports and using the tampered passports to harass and extort money from them.
Yeah, seems a bit far-fetched, but I can imagine this happening with Indians going to work on manual labour jobs in gulf countries for example.
From my personal experience, the Immigration officer at New Delhi airport gave me a hard time when I first went abroad for studies cuz he could see that I was travelling for the first time. That was years ago, havent had any trouble since. But still, each time I am back there, I get the feeling that I have to keep my guard up. If not, somebody will try to rip me off!
Things are and will get better. There is enhanced security in the Airport. Though there is too much crowd at present at Delhi Airport, that might have led to one of those incidents, talks have been going since long to build a new and bigger Airport in Greater Noida with latest technologies. Now again it seems that scheme will materialise soon. And also some of the Metro Airports will be privatised in near future. If you come across any problem at Airport, must complaint to the Airport Director.
Vast majority of Indian custom officers are corrupt.Before globalization,they used to take money from someone who used to bring foreign electronic goods.People used to give them as import duty was too high.Now these are some different ways of harrasment.Don't forget that people who carried out serial bomb blasts in a country few years ago took the help of Indian custom officers for bringing the RDX material.
I didn't read the link you posted, but tampering of passport reminds me of my frustrating experience in Mumbai Airport a couple of years ago. We were flying out and the officer there checked my passport for about 15 minutes, I couldn't look into his desk, but I realised he was doing something like scratching ! And then he told me "the photo looks tampered, did you do it ?!" That was the first and last time I flew through Mumbai.