As an experience designer and a digital agency owner I've been watching various on/offline businesses for the last 8 years. It still surprises me how often bright ideas burn out just because of the fear of risk and irresponsibility of business owners. They are afraid to invest time and funds into one of the most important business elements - the visual look.
Just remember that people judge by the cover. They will judge your personal appearance and they will judge your business's appearance as well. The same way as you will judge them. That's the human nature!
So if you ask yourself does your business need a professional look the answer is YES. It doesn't matter if you sell candies or startup ideas. You wish to impress investors and attract leads but you can't contact each one directly so let it be your logo or your website that makes an impression!
Don't be afraid to invest into the appearance of your pitch presentation as you are not afraid to brush your teeth every morning or get a monthly haircut. Trust the professional who knows his job well. Listen to an advice from other businessmen of a higher rank.
Just remember your business has a LOOK. Use it to IMPRESS.