Usually use company-i-buy-from@mydomain.ninja whenever I make online purchases, and I had a guy from a small shop call me up and ask why I had an email with his company name on. Took some good fifteen minutes to explain him that I was legit and owned the domain. He was still reluctant in the end, but eventually ended the conversation with something along the lines of "it's your problem, not mine, if the parcel won't reach you for using a fake email" :)
That said I've caught and blacklisted quite a few bad actors this way, AND filtering is easier. So worth the occasional weird interaction.
I did this for a decade and decided it was't worth it, nor the plus in gmail addresses.
It was a ton of effort remembering which address I used (I have multiple domains, too, oh joy).
I would end up with multiple accounts on websites, and support calls were super painful.
Eventually I switched providers and realized that in all that time I literally never found any "smoking gun" of a company selling my info.
And the plus email addresses were super useless because spammers know they can just strip out the bit after the plus. Duh.
In fact, my "real" email address that kept super secret and never ever ever gave to anyone except real in-the-flesh human friends (and thus never got any real email to, lol) was by far and away the most compromised email address. Stratospherically compromised.
same! A long time ago I registered an adobe account with the email "<username>+fsck_adobe@gmail.com"
Adobe then got hacked and their account database leaked. Later I got a personalized spam email for a dating site sent to the same +fsck_adobe@gmail email. I complained, and they claimed innocence, saying they got the email from some sort of contact lead service. I then got in touch with that contact lead service's CEO, and of course he had "no idea" how that email got in there. I'm sure they knew very well how it got in there, and after I reported it, they just removed everything after a "+" on @gmail.com emails...
then to ${my_initials}${random_few_digits}@${my_domain} to be able to hand out pre-generated email addresses of mine even offline, and bookkeep who has got which random number at my side internally.
this raised the least eyebrows so far.
The funniest experience was when searching a VoIP provider. One had it in their terms that their name must not be part of the email address. Well, no chance to get my business then.
Never going to know what reaction I'm going to get.