When I worked as an assistant and then as retoucher there was an universal law for the “majority” of the shots the images have to be beautifully sharp and detailed otherwise they are trash. However purposely leaving your main subject (or even your whole shot) out of focus can also create stunningly dreamy images.
If you want to explore purposely ‘unfocused’ images you might choose to selective focus on a seemingly unimportant element of the scene (do this by choosing a wide aperture which will give a narrow depth of field and focus on something in front of or behind your main subject). There is also the possibility to get the whole image out of focus by choosing to focus well beyond or in front of your main subject. But be aware that getting things too unfocused and you’ll end up with a completely unrecognizable subject – the key is to have enough focus for it to be recognizable but out of focus enough to create a wonderful dreamy mood.
Most of the time, we want our photos perfectly in-focus. We spend hours in postproduction to squeeze every last detail of a shot… (and sometimes the adjustments are too much forced). The quest for tack sharp photos is something most photographers are on – but sometimes it is a lack of focus can really make a shot what it is.