What about a realist who could say competition or a lack of volume will erode your profits? Simple bots can be exploited it happens every day.
Micro bids are one way to fool bots. A bot needs to see the market depth and react to new bids and asks to work most effectively but that's more hardcore programming.
RE: Market Making Profit Estimations on bitshares and Steem-Engine Markets - (Staggered Orders)