Do you hear the sarcasm in the title? If you don't, don't worry; I don't know how to be sarcastic. Almost everybody has allergies. I hear complaints all the time; Most are from myself. So, with my own self-proclaimed expertise in allergies (only to the things I'm allergic to), I will now proceed to say why they can be a good thing. Kinda-not-really.
1. It's a great icebreaker
When I play "Three Truths and a Lie," I am never in short of 'truths that sound like lies.' "I'm allergic to trees", "I'm allergic to grass" or, my personal favorite, "I'm allergic to life" (this one might be a stretch). Additionally, when people ask me, "What is an interesting fact about yourself?" that isn't difficult to answer either. "I'm allergic to Dermatophagoides farinae Hughes" or dust mites, as it is more commonly known. Moreover, meeting someone new? Lack of interests? Ask if they have any allergies. If they don't, you can wow them with yours; if they do, then you have at least an hour-long session of complaining together.
2. It can be used as an excuse
I recently took a blood test to see what I was allergic to. Three pages came back--and there were some I had no idea what they were. Here's an interesting one that popped up (and pretty much the only one I really remember): cockroaches. (DON'T ASK ME HOW. LIFE.) Now, if you're Taiwanese or of Taiwanese descent, there are a lot of those there. Before you think I'm suggesting sanitation issues, that's not the case. It's just more of a fitting habitat environmentally. There's roaches everywhere, but you can see them more commonly in Taiwan than in the US. (Granted, there's a lot less space for you to encounter one, so chances are higher) Basically, I hate roaches, and bugs in general, now that I think about it. This is when I employ my "I'm allergic to them, I CAN'T KILL IT YOU KILL IT YOU KILL IT KILL IT" tactic. It always works.
3. Escaping those people who encourage you to "eat healthy" constantly without taking into account you're a poor college student who, at the moment, just really wants some comfort food
These people are well-meaning, but they don't really take your threadbare bank account and taste buds into account. They say, "You should really eat more wheat" when you're making a sandwich, or "let's add walnuts!" to your cookies or even "you should eat baked seafood instead of fried chicken" when you're at a restaurant. When the phrases "I don't want to spend the money" or "I could really go for some fatty food right now" fall on deaf ears, the phrase "I'm allergic to {fill in the blank here}" works every time. That is of course, unless she's your mother and actually knows what you're allergic to.
Overall, this is my own personal experience, and, I admit, allergies are no joking matter. There are fatal allergies that are should be taken very seriously. In all honesty, I'm very lucky. I just wanted to see if I could spin it in a positive light, instead of seeing it with the negative connotations all the time. Kudos to all those with allergies; we have the right to complain! (And I love complaining.)