My MIL has a “signature scent”. She has worn the same perfume for a couple of decades at least. In small amounts it might not bother me, but she has to bathe in it. Since she has worn it for so long, she can’t really smell it anymore, so she puts it on until she can. Never mind that they can smell her three blocks away and everyone’s eyes are watering.
After we moved to a different city and got her smell out of our system, it started giving DH and me headaches when we were around her. We tried a couple of different approaches to get her to cut back, but all ended with her overreacting. At one point I think I was accused of faking a migraine in order to make her feel bad. Thankfully DH knows better.
Being the wonderful champion of mine that he is, he turned it on her. He told her that even though I don’t play games like that he knows she does, and he was getting the feeling that she wore extra perfume to make me sick, and that she would not be walking into our home covered in perfume again. He followed up with FIL to drive the point home, and she hasn’t worn perfume around us again. Hooray for small victories!