I find Fiverr great, and any outsourcing site for that matter.
Putting yourself in a position with these services that result in you risking or losing money would really require a rethink of your own business process.
Except for small one off logo or video intro jobs, I never outsource anything that I cannot do myself. This means if at worst all I need to do is tidy the project up and all I lose is time, as they are a leverage option not a replacement for a specialist.
For $5/project you cannot go wrong - and make sure you are specific on your expectations for the project ie. explain it as if the outsourcer is a well educated 10 year old.
I use Fiverr to get likes to a new facebook page so I can claim the personalised url, or for nice looking video intros for my web videos etc.
As tempting as it may seem, stay away from
SEO and backlinks etc as you do not know where they are coming from, and could cause irreparable damage to your site ranking.
Cheers & have a great day!!
Steve Fallon