You mean undervalued altcoins that you can short sell? Well, if you want to short sell, you have to be very careful and vigilant while doing so. Some of this altcoins can be a bait for investors to invest after which it dumps. Know what you are doing before starting on a trade
Most importantly, try to see how their project runs and is developed or not. I've seen ESH projects that don't have good value in exchange. but it turns out the price can increase before they do airdrop to get other coins that have good prices on the market. it seems like such a scheme is already known to people with large capital.