Up close, a painting is just blobs. Step back before you decide what it is. People too.

Standing too close gives you detail and takes away the picture. Every brushstroke is a mess at six inches, and the mess is not a flaw, it is what the painting is made of; it only resolves from across the room. People have the same property, which is why one bad conversation can seem to be the whole of somebody.

So step back before you conclude. Ask what this person is like over a year rather than over a Tuesday, and whether what annoyed you is a brushstroke or the picture. The ones genuinely not worth it look just as bad from a distance, so checking costs nothing.