As one word.
A good hairbrush is one that does not pull your hair out and one that feels good on your head! When you brush it should feel like a massage not like a big gorilla ripping out your hair!
no
Underdeveloped should be written as one word, not two words or hyphenated. I hope this answered your question. :)
One word is fine.
"Bloodthirsty" should be written as one word.
Taxpayer should be one word.
One ten thousandth
There are a lot of hairbrush cleaners out there that will help people to clean their hairbrush. To name a few chemical products, one could mention Siege Cleaner and also the chemical bleach.
'Noone' is not a word. If it were, i would be pronounced like 'noon', which means 'midday'. It can be written as no one or replaced by 'nobody'.
Under garment should be written as "undergarment" since it is all one word in properly written English.
Look in your comb or hairbrush.
Denman has their own website on which one could purchase many of their products including the hairbrush. There are also many other websites that offer such products.