Curse or Monster with lasting Bad Stuff?

[UncleBob]

So, when I've been playing, if someone had a curse or a monster that had some kind of lasting effect, I've had the player place that card in front of them so we'd all remember that it was in effect (until such point as it was no longer in effect, of course). Some cards already say to do this - which leads me to believe what I've been doing is technically wrong (otherwise, why would they need to say anything?).

Of course, this comes into play when someone gets the ability to draw from the discards - if they want to redraw a monster or a curse that was just played, they won't be able to.

So... am I doing it wrong? Should the card be discarded and we just have to rely on our own memories that the player is under some kind of bad stuff?