Olliebeak. I am a 'decanter' too. I don't have to watch the pennies, as I did when bringing up 5 children, but I hate to see things wasted. The last half inch of handwash goes into the new bottle. The last bit of sauce in the bottle either goes into the new one or is washed out with a drop of water and goes into the stew. Washing up liquid bottles are rinsed out, and there is enough for a few more sinksfull. Plastic tubes have the ends cut off, resulting in me finding quite a lot left hiding inside. I fold over the end and seal it with a clothes peg.
The only thing that doesn't get the treatment is hand cream. I can't keep up with all the tubes and bottles I receive as gifts, or win on the tombola stall at charity do's, so I tend to be a bit more cavalier with them.
I think that we 'war babies' were so much exhorted to scrape the butter paper and the jam jar, and use up or re-cycle every little thing that we have a guilt-trip at the thought of wasting anything.