It's disheartening to see HR still practice this and requesting for pay slip is one thing but than they didn't promise anything at all to the candidate even after revealing your pay slip.

But one should not show your pay slip . When the manager or HR ask for it during the interview ,try to interrogate them further.

1) why you need to see the pay slip?
2) So, you have doubt that i reveal a fake previous salary?
3) Than in the first place y u calling me for interview ?
4) Do you call me for interview because I have the skill for this vacancy ?

Once you have detect something fishy or fiction about their conduct, i mean do you still want to work for them???