I was thinking about blog comments spam for hard to cover niche (adult/casino/pharm) an others stuff like that where you can’t just put a URL like www.extracheappokerchips.com because you are gonna for sure being filtered by plug-ins like askimet or manually deleted by blogs admin. But there is a strategy you can use that could pass most of the filter.
First, you need a domain name that sound “legit” and that you don’t really care about. Once its registered you have 2 strategies you can use to bring some trafic / links to your domain in a harder to spam niche.
First strategy, you simply 301 the new domain to your harder to spam domain. This way you get all the links and trafic directly to your domain and if the blog admin don’t take the time to click the link (and only see something like www.mypersonnalboringblog.com ) he will probably don’t filter it. So you will get the backlinks and traffic directly to your money domain, cool no ?
Second strategy is kinda the same than the first, but a little more evoluated. You just put up a real website/blog on the temporary domain than when you have the amount of links/traffic you want on it, you 301 it to your money domain. you can using this way add a couple social media frontpages and backlinks to the domains using word that you want backlinks on it without looking like a let’s say casino domains. So you make a post about “chips” (as in “poker chips”), a post about russian roulette (as in roulette) etc… Than when you will 301 the domain to your casino website, all the links will sill be targeted 
Don’t abuse those methods but they are very hard to track black hat seo strategy that can give awesome results.