Three quick eyeball checks before doing full verification:
Length
Exactly 56 characters before the .onion suffix. Not 55, not 57. If your paste is a different length, either you copied wrong or the address is malformed.
Character set
Lowercase letters a to z and digits 2 to 7. No uppercase, no 0, 1, 8, 9, no punctuation. Anything outside this set means the address is not a valid v3 onion.
Prefix
Current WeTheNorth addresses use a consistent prefix chosen by the operator. Compare the first several characters of your address against the reference. Any deviation is a signal.
These are eyeball checks, not verification
An address passing all three still needs to be checked against the current signed rotation before you type a password on it. But an address failing any of them is guaranteed wrong.