It's a combination of "suck" (in the negative slangy sense) and "fantastic". It's not even a common expression, so I wouldn't worry about it too much. Clearly, the writer invented it for the text. It's just an extreme version of "it sucks".

It's a totally made up word, from putting together 'suck' and 'fantastic'. It basically means a job that fantastically sucks. A job that people hate to do. So maybe unblocking drains could be described as sucktastic. Generally though, what comes to my mind is crap jobs for bad money and which generally make the employee feel miserable.

Description of something that has achieved a new and ultimate level of sucking, such that there is almost something fantastic about it. I get this meaning from urban dictionary..