Hello there,
Like Joseph says allot of people thinks that Google doesn't give them penalty for the spammed links. That is NOT true, i have ben testing that fact and actually even tho Google knows that a site is a spamming site, they will give you penalty untill the current domain / server IP is blacklisted by Google.
To blacklist spammers theres actually only 1 way:
Disavow the links comming from spammers, as more and other site owners will disavow the same domains / ip, the faster Google will blacklist them. If you aint sure how to Disavow and make sure you dosn´t disavow some urls that is known as a good site on Google, coz that can also make you suffer a penalty on youre rankings. 
So a good tip is to check the page Aut. and domain age, if it is an old domain with allot of Aut. You need to ask the siteowner to remove the links, after that and if they dont remove the link, you can Disavow followed with a message to Google regarding youre dialog with the websiteowner refuses to remove the link to youre domain.
