On our site, we have a tag field that looks like the following:
Today, while looking at some of our users interacting with the site, I noticed that one of them had used only spaces to separate their tags, instead of using commas as the input field advises (he probably did not see the advice and applied his idea of how tags should be typed in).
This raised a concern: are we going to get many users that fail to read the advice and end up typing in tags by only separating them with spaces (which would lead to having a huge single tag) and if so, should we try to do something about it by educating the user about the problem?
I thought that we could make the field detect if the user has entered no commas in the field and check for the presence of more than one space, and if the condition is met display a warning that would say something along the lines of "You might be typing in your tags incorrectly. Are you using commas to separate them?".
If we didn't tell our user about this issue they would probably have a hard time noticing and correcting the issue after submitting their entry, because the only difference between well-formed tags and "huge chunk" tags is the amount of space that goes between them, a thing which a novice and uneducated user might miss.
Is it a good idea to try to prevent this behavior and try to educate the user a priori? Are we taking the right approach?