Fat fingers are mostly a thing of the past. Such a thing is so rare these days as some exchanges have some measures to safeguard the trader but back in the days of exchanges like Etherdelta, it was something to look upon.

If you are thinking arbitrage, then I would advise you to tread carefully. Some of those small exchanges could either be scam or they could be old exchanges that just decided to block withdrawal of some coins indefinitely like HitBTC or Yobit

That’s pretty risky if you trade in smaller exchanges the strategy you might be talking about is by buying cheap from other exchanges and become a market maker who provides liquidity and makes a profit on the spread.

Or you might be talking about crypto arbitrage the only risk here is pretty small but if you trade in small exchanges or unknown exchanges that is pretty risky. There are many guides out there on how to arbitrage trading.