IFR Passengers?

What are your standards for taking passengers up into actual conditions?

I've developed a decent feel for what people will tolerate VFR- who can take
a few bumps, who will get scared if its windy, etc. But I haven't got any
idea what to make of taking pax into the soup. Is it as disorienting for
them as it is for an untrained VFR pilot? Are they usually OK so long as
it's smooth? What do you tell them before you take them into actual for the
first time, if anything? Anybody ever have somebody get real scared, how did
you deal with it?

Just a few wonderings from a pretty green instrument pilot...

Best,
-cwk.