This blog is published primarily for the link it shall be given from a group I belong to on Facebook, the Language Pedantics Association, and will probably be of no interest to anyone else, but you never know.
Now, as I've said before, I'm not really as pedantic as they say I am. I like to have fun with language. I don't believe it's necessary to write in formal English at all times. This is not a thesis. And perfection is absolutely not necessary. You should not need a degree in English to write a blog. Nobody cares if you don't know how to use a semi-colon, or if you can't spell phthisis.
If you deliberately use non-standard English for fun, then it's fun. In social media slang is perfectly acceptable. I have no issue with dunno, gimme, wassat, etc. But I honestly think some people do value the help they get with little tips on how not to make actual grammatical errors.
I have many times mentioned the error of "I use to" instead of "I used to". I see very highly educated people make this mistake. Spellchecker won't pick it up. The reason people write this, is because in fast speech the two sounds of D and T can't both be heard.
If you substitute other words, you quickly see that a D is required on the end of use.
I used to go to Paris.
I wanted to go to Paris.
I loved to go to Paris.
(The two distinct D and T sounds can't really be heard in loved either, but for some reason, you don't see that one written wrongly.)
So, I have passed on this tip: try substituting a different word, if you're not sure.
But it's not that people are not sure. They don't stop and ponder over it. They write quickly, and don't notice the error. They may do if enough annoying people like me point it out, but I'm never rude enough to do so at the time, only in blogs like this. So, you may be a culprit, reading this, oblivious to it.
This cropped up on a forum and it was pointed out to me that it is a bit confusing because when it's in one negative form, the D ending is not correct. I'll explain.
"Didn't you use to go to Paris?" is correct. Apparently this is confusing. Well, no it isn't, and it's also not a big deal.
How often do you say things like that? Seriously, I don't think I've ever asked that in my life.
But if you do, just substitute another word to check!
Didn't you like to go to Paris?
Didn't you want to go to Paris?
I can explain why this is, with verbs used as adjectives, and the complexities of auxiliary verbs, but honestly, you don't need to know all that, just know that despite all the weirdness of English grammar there is a certain amount of regularity that helps you.
"I use to" is wrong. There are no exceptions to this.