I used LogoDesignGuarantee.com once with generally good results. For the price I was happy with my logo choices and while they did not exactly meet the deadline, it was only $50 and the final logo was decent.
Fast forward a few months when I decided to try them again. The initial interaction was again decent. I was given 6 logos to choose from and after choosing the winning design a few simple edits were made and I was shown the watermarked "final" version. This however was the last I was able to contact them. Their 24hr live chat is never online and their 24hr phone support number consists of a voice mail system.
Looking at my dashboard today I see that all of my logos have been deleted. The page says the project is "in progress" but the logos are not present. Luckily I saved a version of the watermarked copy and I can just photoshop it clean.
It's true, you do get what you pay for.