Our current understanding of allergies are that they are defensive measures launched unnecessarily against benign intruders like pollen, which is mistaken by the immune system as a threatening foreign invader. The concept of immunotherapy is based on this logic: By exposing the immune system to small consistent doses of a benign substance like pollen (say, through honey, deliciously), the immune system will maintain antibodies to combat the invaders and forgo any need to launch a full-on attack.
This type of thinking is at the heart of what's called the hygiene hypothesis. There's a great debate over whether raising children in an overly-sanitized environment is actually detrimental to the development of their resistance to allergies. The hygiene hypothesis says dirt don't hurt, as it were, and not allowing kids to be exposed early on in their development to a bit of grime here or there sets them up for large allergic reactions later in life when they are inevitably exposed in places like school, where they encounter other, more disgusting children who aren't as pale or shy as they are.
Overusing bleach-based cleaners is one contentious issue; same goes for antibacterial soap. There's a strong suspicion among perfectly sane people that the overexposure of disease-causing bacteria to everyday antibacterial or antimicrobial compounds creates a resistance to these formulas, since bacteria evolves at an alarming rate (the fastest bacteria go thorough a generation in 15 to 20 minutes). It is these products that are thought to have given rise to so-called superbugs like MRSA.
The same thinking also goes for feeding antibiotics to the livestock that eventually ends up in our stomachs (or whose dairy products do); given enough time, bacteria should develop a resistance to such measures. This is why people who've always said that introducing antibiotics to livestock was a bad idea are feeling very smug right now.
Ars Technica reports that Arizona researchers spent some funding on steaks purchased across the U.S. Tests for bacteria strains found that a full quarter of the sample steaks were home to a Staphylococcus that is resistant to at least three kinds of common antibiotics. Fully half of the samples had bacteria that was resistant to at least one type of antibiotic.
Which means that when you eat of the flesh of the filthy swine or drink of the milk of the sacred cattle or just have a nice fried chicken leg you may also ingest this bacteria and will probably die a slow, painful death by rotting from the inside out. Perhaps nothing this drastic, sure, but you can imagine those people in the not-too-far-off future who die from infections from bacteria we previously had licked will lament the overuse of antibiotics in our gleaming clean culture. [youtube=http://www.youtube.com/watch?v=2FZYLJNNJlo]