If you're using a high-wattage device (50W or more), stay away from high-strength salts. The excessive nicotine delivery can make you feel sick. Similarly, if you're using a small pod system and you fill it with freebase, you'll likely get a weak hit and poor flavor because the device isn't designed for that liquid.

Also, if you're a heavy vaper who likes to chain-vape, salts might not be ideal because the fast nicotine spike can lead to overdoing it. Freebase lets you vape more casually without hitting a nicotine ceiling.