Potentially it may be referring to bluffing into a dead pot. eg. one person all in, you and villain still have chips left, no point bluffing into a dead pot.
With a semi bluff I think often you do want to be 'inflating' the pot since a) a bigger bet gives you more fold equity, and thus a better chance of winning the pot there and then, and b) if your opponent calls and you hit your outs, you win a much bigger pot, yet also easily can fold to them when you miss and c) balances out your value bets so it is harder for your opponent to discern whether or not you are betting to get value or to induce a fold in any given hand.
It doesn't really matter exactly what it means, catakliss is right, instead of thinking "Never do x" type things (which are easy to avoid huge mistakes when you are inexperienced) its better to think along the lines of "why am I making this bet, what do I expect to happen as a result of this?"