The phrase "fine comb" means to examine or search in great detail or with extreme scrutiny. It is like when you carefully inspect something using a comb with very close teeth. Full definition
It also gave investors a ton of confidence about its assets, as the FSA has just been over Barclays» books with a fine comb / bomb detector. (monevator.com)
«People, they don't have that fine a comb, I think.» (politico.com)
• Fine comb • Blow dryer • Decorative hair elastic or Love In Tokyo hair - tie • Soft round brush • Rat tail comb (stylecraze.com)