Surely it's not as simple as 'If you get a massive amount of backlinks in a short period of time, you'll be penalized'. I was just thinking, what if you were a forum regular with 14k posts, then one day you change your signature to someone else's website. The website owner would then get punished over someone elses action they couldn't control? Am I missing something?
IMHO you can not be never penalized for incoming links. If yes, this can be very simple exploitable in competitive fight.
My dear friend You will never get penalize for getting huge number of links from another site. If you get tons of backlinks in very very short period from other website then it is impossible to be banned by google. Google is not so fool, if this happen then our competitor start building C grade backlinks for our site and can ban us. You will get banned only if you get huge number by black hat seo unless it is impossible. Yop may get banned if you post huge number of post for very short time and then stop foreg. you post 10k or 20k links in 1month and then immediately reach to 200 to 500 backlinks per day. this means you have used some automated software and done spamming in others website by posting spam post or spam links or have purchased huge number of links from link seller. Cool mate and Enjoy your day