Great designs are not easy. They require tiniest bits of attention. But novice designers can overlook the minute details and make the great sin of overdosing the customers with unprofessional logos.
A logo is something which holds the identity for the brand. If the job is assigned to a non-professional designer, the outcome seems like a great sin. If the logo is not well planned it may lead to confusing the customers with a different message.
If the logo is not designed with care it can lead to shapes, and fonts on the board with no meaning at all. There should be some tips that a designer can that can lead to a memorable logo.
Here is an excellent infographic by Brands Design which can serve the new designers or even the old ones and protect them from committing to do serious sins.