I disagree with this soo strongly. MOST monster like creatures don't use incants they say things like "Magic <effect>" When you are playing a role that actually uses the whole incant its really important not to make any mistakes in the incant. These incants are how magic works and as an npc who is there for entertainment and can just repop and try again if someone calls a miscant on you you should learn from it and try again on your next pop.
In fact I feel the exact opposite if a PC has a minor stutter I am way more likely to let it go than an npc because they don't get to just come back with a full pyramid and they are paying to have fun. Now I am not saying berate the npc for miscanting or treat them poorly but just call it and let them know what they did wrong and carry on.
Treating anyone poorly for any reason isn't good.
In fact I feel the exact opposite if a PC has a minor stutter I am way more likely to let it go than an npc because they don't get to just come back with a full pyramid and they are paying to have fun. Now I am not saying berate the npc for miscanting or treat them poorly but just call it and let them know what they did wrong and carry on.
Treating anyone poorly for any reason isn't good.