Apologies in advance if this comes over too harsh or seems rude, it's not meant that way and neither is at directed an any individual(s). Also, I'm speaking from a mentalist's viewpoint, I can't really speak for props used in coin or rope magic for example.
Let's start with defining 'examinable'. To many people this means to be put under close scrutiny, obviously something we want to avoid with most gimmicks.
To others, such as Iain (and myself), it means 'appears to be normal and its normality proven or implied' - Iain's dry pen being a perfect example.
The only reason something really needs to be able to be put under close scrutiny is if your performance is utter... rubbish. To quote a man far better qualified than us here...
Magicians do tricks with pieces of paper. Mentalists read minds.
Your performance, the drama, the emotion etc etc should be so utterly convincing that the clear plastic bag you had a volunteer pick a pay envelope from is completely forgotten before you've even finished the effect.
If, in Eshly's recent Q&A example you cannot find suitable gimmicked envelopes to peek into then either don't use envelopes or don't peek them. Problem solved. Everything is perfectly hunky dory.
Hopefully I don't need to elaborate any further
