Billybob
No, actually he's correct. In the days before kerning, many fonts had letters which would extend beyond their start and escapement points. The effort was to compromise between the correct letter spacing for e.g. "YY" and "AA" [which should be wider] and "YA" and "AY" [which should be narrower].
To test for kerning, it's necessary to have a kerning pair of letters which appears in both orders, with identical letters to either site.
For example:
AYAY ffYYIf the letters are kerned, the second line will be slightly wider than the first. At least on Firefox, the two lines appear the same width. The two "A"'s and two "Y"'s on the second line will touch each other slightly if the fonts are not kerned, though it's not too bad. But look at "fY". On a properly-kerned font, the letters should be separated. But without kerning not only do the letter spaces overlap, but the letter forms themselves do. If someone had an "f" and "Y" in lead type which projected past the outsides of the main type blocks (I have seen lead type which did that), one would have to put a small spacer between the letters to avoid damaging them.
AAYY fYfY
Those were the days, my friend. All of this has reminded me of how much I love Word.
http://commfaculty.fullerton.edu/woverbeck/dtr5.htm