Always have a decoy wallet, in this wallet you must reserve a amount that you are willing to lose (something like US$3 ~ 50) when testing a new wallet just downloaded, you enter this test decoy seedphrase, after all, these fake wallets usually have a malicious code to drain wallets immediately as soon as a wallet with amount is imported, so if your decoy wallet is drained, you will know right away that it is a scam wallet.
Should we use our funds to test for fake or malicious wallet? The points you stated above may be right to some extent but to be rank, you have to make sure you are downloading these wallets apps from the right source, which everyone knows as their official web. Play store, can no longer be trust so even if you are downloading from Google Play store or other official stores, you should make sure that the website redirects you there. Don't click unknown links to download so as to avoid downloading Trojans or malicious apps.
This way, you don't have to test the authenticity of the wallet with your funds or having to try a decoy just as you stated in your op.