spotting a bluff

another thing i've been trying to do lately is spot bluffs

here are a couple

obvious attempt to steal the pot: calling down a pot size bet on the river with ace high after no action on flop or turn

this is a tougher one but i think there is no way he plays a big hand like this and i have lots invested already: my ace high flush draw turns from a semi bluff on flop and turn into a bluff catcher on the river