Me too, I rarely get bitten even without repellent, and when I do it's completely gone (the bump) in hours. For mosquitos that is. Undesirable body chemistry??

I guess the biggest problem I have with repellent is it removes paint from my gear and melts some synthetic fabrics and permanently stains others. OTOH, I have caught serious diseases in Africa from mosquitos. All it takes is one bug bite. Some can stay in your body for years and manifest when you're weak from something else. Some of those diseases or similar are migrating to here. So I'm doing the repellent thing again, trying to stay with the more modern formulations around 30% DEET that are slow release. From what I've read, many of the more sophisticated ~30% formulations are similar in effectiveness to the old 100% DEET styles. But I carry the old 100% DEET (AFAIK now "illegal" to sell in Canada) JIC it gets serious. Or I become attractive...