We cannot call it a scam until the new altcoin is stopped being traded. It's not like the coins traded on small exchanges are all scams but some coins obviously diminish from the market. We should be careful while buying the coins that are listed only on 1-2 small exchanges with low trading volume and should avoid buying such coins also. Yes, sometimes some coins on small exchanges have high withdrawal fees which is not a good sign for any cryptocurrency in my opinion.