If I keep a plastic mineral-water bottle topped up with tap water and regularly drink directly from it, the neck smells vile after a couple of weeks. Why is this and why is it always exactly the same smell?

I have always wondered if a strong smell can wake you up immediately like a loud noise.

The smell of aromatic karoo bushes in South Africa is famous for giving the meat of sheep that eat them a herbal aroma. It also affects their lanolin. Even after repeated washing, any clothing that has come into contact with such sheep retains the smell and also affects other clothing in the same wash. What causes it?

Bess and Jon Richfield, Somerset West, South Africa

This summer it was very hot in Europe and when I was on holiday, I even had to wash several times a day. I heard many times that it is bad for the skin to use deodorant on parts of the body exposed to the sun, but also bad to use washing agents like soap more than once a day. So at first I tried to wash with water only, not using soap. After the general, salty smell of perspiration had gone, there remained an odour that strongly reminded me of a "Dané" deodorant. Later I found that the shower gel "Dove silk glow" also smells somewhat similar.

I had none of these with me on my trip! Do they contain a component that is also a component of human body odour? If so, what for? If I use them won't people think I have washed with water only and am still dirty?

Recently, I have had a bout of exma in the small space between the top of my ear and my head. Whenever I scratch behind there, my finger smells like very strong (and slightly off) cheese for about half an hour afterwards. Even after the exma has gone, the smell lingers. Is there any reason for that?

I can cope with most nasty smells, but the smell of someone else's vomit always makes me feel sick.

Why is this?

Flowers co-evolved with their pollinators: that is why they find flowers attractive. This arrangement works to the benefit of both parties, so do humans get any similar benefits from liking flowers? The plants do, in that gardeners propagate them.

Come to think of it, are other mammals attracted to flowers?

Jim Simons, Cheltenham, Gloucestershire, UK

My daughter is nearly 4 weeks old and she has that 'new baby smell' which my wife and I find absolutely lovely. We have so far only bathed her in clean water (no baby-wash or soap) and have only used lotion a couple of times when she's had dry skin, so her smell is all her own. Is this some sort of evolutionary device to encourage us to take care of her? Would other people find our baby's smell as lovely?

Our smelling sensors are inside the head. Our noses are vulnerable to damage and the majority of primates and other mammals manage with relatively flat faces.

Dennis Newland, Purley, Surrey, UK