The most detrimental thing you can ever do to your startup is to outsource to a company that doesn’t have the skills or knowhow to get the job done properly. And even worse than that, is if it has bad business ethics, and is ready to not fulfill their end of the bargain if sh** hits the fan, and it does hit it a lot of the times. There is no bigger time and resource waster then that. So, even if its a bit of a hassle, do proper research when choosing to outsource, ask, read reviews, even go so far as to talk to references of that firm if need be (i.e. companies they say they worked with), because the alternative is a hundred times worse.
p.s. Clutch.co is a good tool to check up on tech and marketing firms