I don't have any blacklisted altcoins since they just come and go after that I just simply ignore or decide not to have them especially if I know that there's nothing to get or even there's no chance for that alt to get a pump again.
But in case of taking precaution discussion about alts then provably I am avoiding those meme coins especially if they already exist for long period of time even if they are listed on big exchange since we don't know if we can able to get something from them since I'm afraid that by the time we are going to decide to put up some money to those meme coins then they would start to leave on the ecosystem and pull of the rug pull scheme which has been played by a lot of scam devs for so many times.
No, not all alts can come and go but some remains, and I believe the OP is referring to them. Before we mistakenly pick them sometime and ruin us, it's a good idea to act first/early and blacklist them right away.
Alts (the normal and good ones) are I think different from meme coins and in fact, they are not even a coin but they are a token. If we are interested at them, it is still better to choose the established ones because the chance for them to collapse right after we invest is only small. We can get something out of them, once the meme coins are trending. It was like they are having their own bull run too. It's fine if you choose to play things safe. In fact I like users like that, who only support cryptos that has real contributions in this space.