I'm a bit of both. I throw out foods that smell dodgy (sometimes my imagination maybe?). But I take no notice of use by dates - I just do the sniff test, sometimes the touch test too. If sausages or bacon feel 'sticky' then they go in the bin, not worth chancing.
The cut edge of peppers are inclined to get a bit slimy, but the rest of the pepper's usually OK, so the edge gets sliced off and put in the compost bin.
If cheese develops a bit of mould, I slice it off and use the rest. If it hasn't been wrapped properly and starts to go dry, I wrap it in a piece of wet cloth to rehydrate it - 24 hours later it's good as new!
Some jams can go mouldy on the top, even when stored in the fridge. That gets scooped out, discarded and I use a clean piece of kitchen roll to clean the inside of the jar above the jam line. Everything underneath is absolutely fine.
Apart from food, there's fabric! I'll save a garment if the fabric is good and I might be able to use it. I'll wash it, take it apart, discard waistbands, collars, seams etc and save the rest. Buittons get removed and saved. Even the ribbons stitched into shoulders for hanging get removed and saved!