OOC:
To cast Counterspell you must see the character casting a spell, which can be interpreted both as seeing the character and the casting. So if the character is hiding, is invisible or is a sorcerer using subtle spell, you can't cast Counterspell.
Nevertheless, I usually judge that V and S components must be clear and evident, so you can't whisper an incantation or make small motions with hands and arms, unless the spell description says so. There are no rules, as far as I know, saying you can't pretend to be casting a spell, however. Spellcasters may know the difference, of course.
I think it would be perfectly within the rules to try to pretend to cast a spell when actually using non-magical misdirection to achieve an effect.