Of course some people argue that in today's world of instant communication you don't need good grammar; that as long as you communicate your meaning, that's good enough.
I can actually see that as a valid point of view, although I disagree of course. Most of my friends know that, as well as music, I've always worked with words. The words we use define who and what we are. That's a sweeping statement I know, and it's not lifted from anywhere. I just this minute made it up. Words are knowledge, and knowledge is power. The power to communicate what you mean in the best possible way, so there can't be any misinterpretation of what you mean.
To be honest, in the case here, probably not. It's only pedants and sub-editors like me who'll notice, and you can argue that this sign gets its meaning across perfectly well to clients. Nevertheless, it's wrong. What's really interesting is that they've actually put a hyphen in the correct place. "Pre-loved clothing is right. Which brings me nicely on to the hyphen.