Tommy Boy, one of my favorite movies of all time. The line from the title though holds very true to the glyph industry.
Lets break apart the sentence... selling a ketchup popsicle to a woman in white gloves. Pretty much your selling something that is discussing, not useful to someone that will probably make a mess on themselves and end up looking retarded.
Practical real world (of warcraft) application... your most profitable glyphs are going to be the most useless peices of crap that people should not buy. You are not going to sell many of these glyphs however... maybe 1 or 2 of each type every week - but they WILL sell and they WILL give you more profit than any others, simply because there will be less competition to sell these glyphs.
With 3.3 getting ready to release in the next week or two I'd recommend stocking up on herbs/inks and pulling your glyph supplies up to +2 or +3 of your normal amount. Be ready camp the AH for the first day or two after the patch, as this is when you'll make the majority of your 3.3 profit.