if you have used a dropper flea treatment on the back of its neck, it will work. and cats do like to roll in dust, so maybe what you had on your arm was a little bit of what i call 'fust' that they pick up. yes all cats, dogs and other critters have fleas, but then so do you! if you keep them under control, there is no reason that you or your house will become infested. Yes you can spot fleas on cats, they are easier to spot in lighter coloured fur (obviously!). if he is infested it will be obvious - scratching, rolling and bald spots/scabs appear on the skin. lighten up and give him a little love! i remember once rescuing a baby squirrel that had fallen out of its nest and despite waiting for hours from afar, its mummy did not come to retrieve it. so, i wrapped it in my jumper and took it home and did not realise until i had got there that the fleas were literally hopping off him in their droves and onto me - i mean, you could literally see a migration! after much screaming, hopping and stripping off in my back garden, i managed to deflea myself (much to the amusement of the neighbours!) and ensured the little critter stayed outside until the rspca picked it up. now - that's a flea problem! your little gent or lady will be fine to have in the house and will love you greatly for the rescue x