Isn't it one thing to just "list" a project after the team has paid the listing fee and another thing to "promote" it in any way?
For example Crypto-Bridge has a "benchmarking" system to mark some coins/tokens as high quality. (
https://wallet.crypto-bridge.org/benchmark)
Would you call Crypto-Bridge shady or untrustworthy if they listed a scam coin which they have not marked as "benchmarked"? Personally I wouldn't, because they haven't give me any sort of investing advice. However if they ever mark a coin as "high-quality" and it turns out a scam, only then I won't ever trust their system again.
I believe it should be up to the users to do their research before buying any random coin. I see exchanges as a middleman and I always act with the belief that they haven't filtered any of the coins they add
(with only exception maybe being Coinbase and Kraken, I tend to view whatever is listed there with a positive bias).
If we were to judge exchanges based on what they list, that'd leave much open for personal opinions.
For example I believe that BCH is a scam... some others believe XRP is a scam... Or are we going to consider scams only the projects that dump their premines the moment they hit the market? All the projects that slowly steal people's money are consider OK? If that's the case then is any exchange supposed to predict that outcome?
Or should an exchange accept the warning of the community before listing a coin? Just like a lot of BCH-supporters are calling BTC a fake, I'm sure something similar will be happening with smaller-cap coins. What is an exchange supposed to believe?
And one last point...
If exchanges were to filter the coins they add, then that'd be like marking the coins they list as safe. Legally I believe it's better for exchanges to either be very strict or to stick to "we accept everyone who pays the listed fee". Right now we have exchanges of both those types.