All tv is about show and tell - they show you some things, tell you other things. Most of the time, the show and tell mesh, but when they don't - I go with what is shown, not what is told.
In the beginning of
Buffy, we were told that vampires were nothing but monsters. That nothing of the original person was in there. Yet in the first two-parter,
WttH/tH, we are shown something very different - Jesse as a vampire is not just a monster, he's a Jesse-monster. He's still Jesse, but without a conscience and with a bloodlust. He still wants Cordy, he wants Xander to get why being vamped is cool. He
is still Jesse, but sans soul.
And as we've learned since then, it is what we were shown that was true, not what we were told.
( spoilers for Shells )