Recently one of my site was spammed with 50000 backlinks coming from 500 referring domains, backlinks source is comments and guestbooks. Competitor used only 1 anchor (Website) to spam my site. Although i do not see any negative rankings yet since my site gets links from high quality sites as well but still i am going to submit disavow file in google. I have already collected 500 spammy domains and all i have to do is submit them.. Anything else i should keep in mind before submitting them? Looking for suggestions from experienced members thanks.