Yea I would say stay away from spamming blogs if that is your intention. You will just get your site penalized or possibly banned.
Having a link profile made up entirely of low quality borderline spam links is not the best way to try to rank for competitive terms. I personally see those links as worth little and not worth the effort.
However if you are looking for traffic you should definitely post quality comments on related blogs as readers may like your comment and want to click to your site and see what else you have to say.