1. Artificial sweeteners
I would rather have the calories of normal sugar than ingest things like Equal and Sweet Low or whatever they're called. There's quite a lot of varying research in regards to cancer and artificial sweeteners, so some things will tell you they are safe and others will tell you the opposite. So to be safe, I don't touch them.
Everything has already been said about this topic: get off the durries.
3. Caffeine loaded energy drinks
We're talking Mother, RedBull, V... that's all I can think of off the top of my head but there is so many more. There is a small place for them (like shift workers trying to stay awake) where their use isn't so bad. But they market towards young teenagers who really don't need them and drink them to excess. Like the 750ml can, sold in the drinks fridge with all the other single serve drinks, yet it says in small print on the back not to consume over 500ml a day.
Okay so Nutrigrain isn't that bad. What I don't like is how they market themselves as iron man food. It has a glycaemic index of 66 (which is moderate, bordering on high), so if eaten like it is supposed to be eaten, as a breakfast cereal, then how is that going to sustain any iron man for the day? They just get hungry again 20 minutes later.
I would use Nutrigrain like a lolly; it's high in sugar but it has got some nutrition to it like protein and iron.
Loaded with sugar. Erosive. Insanely fizzy. Nope.
6. Chewing gum
Again, not something that's really bad, but I just don't see any point to it. You start chewing, your stomach thinks there is some food coming so it starts secreting more acid, but nothing ever comes to neutralise the acid.
7. Glen 20 and the like
That ad makes me cringe, where the lady is spraying Glen20 all over everything. Germs are not necessarily the bad guys! But the ones who ARE the bad guys are going to be in that .1% that don't get killed by the spray, then because they don't have to fight against all the other germs you've just killed, they thrive. If you want to be hygienic, wash your hands.
8. Sodium Lauryl Sulphate and derivatives (SLS, SLES)
This is found in basically anything that is supposed to 'clean', from toothpaste to engine degreaser. I'm fairly sure the current, unbiased literature puts its safe use at around 1-2% (as an ingredient of something). Most commercial shampoos are around 20-30% SLS.
That's all I can think of for now, feel free to add any others you might think of.