is this filter ruined?

[memostothefuture]

I have a filter that shows a persistent smudge film that I can't seem to get rid off.
I tried piping hot water. I tried lens cloths. I tried glass cleaner. still I see this film.

do you think there is a way to get rid of this imperfection?
for the record: this is a hoya pro1 digital 77m pola filter.

http://imgur.com/gcs1Aml

(I know this is technically an accessory but we're talking about glass and I thought it was a better fit for the lens forum. my apologies if I was mistaken.)

[Joel Eade]

It could be an oily residue from your fingers.

I would try a lens cleaning solution or a 50:50 mix of distilled water and clear vinegar.

[memostothefuture]

the lens cloth is brand new.

oily residue sounds right. I will try the water&vinegar solution and the lens cleaner. thank you!