@Melony2 If you have an otherwise lovely stay, the best thing is to give the hosts private feedback making them aware of how problematic all these scents are for many guests. That way, they don't get a bad review, but are being educated about how their cleaning methods are affecting their guests. You are probably a lovely guest as well, and I'm sure they'd hate to lose your repeat business or recommendations to friends over a simple and easily remediable thing like laundry detergent.
And when you are booking a place, it would be good to state your issue in a message with the host before confirming your booking. If you also suggest to them what products they can use that you won't be negatively affected by, and they state that they will follow your directives, it will help both you and them. And remember that they may have many bookings between the time you book and your check-in, so a reminder about your needs for "scentless" a few days before your arrival would be wise.
Some people really have no clue and actually think that artificial scents make things smell "fresh".
I am not allergic, but I find scents like dryer sheets, air fresheners, etc, to be revolting. They are anything but "fresh", they are chemical and hazardous. I always travel with my own pillow because of this.
While I do use regular laundry detergent, I never use fabric softeners and all the laundry is hung on the line in the fresh air and sunshine for a day, so there is no smell left, at least not that I can detect. And I'd never spray air freshener or anything else around either the guest quarters or the rest of my home.