Posting the logos of huge companies signals to small companies that they're not your target market. So if the office manager of the IBM facility in Mobile, Ala

Posting the logos of huge companies signals to small companies that they're not your target market. So if the office manager of the IBM facility in Mobile, Alabama uses your SMS service to coordinate the contract janitorial staff, then boosting the IBM logo without this context sends the wrong message to the long tail of small companies who don't pay "IBM" prices for anything.