Number one-google will not penalize you for using stock photos...absolutely not!
Blue is an excellent choice for cleaning company colors
Blue and yellow,blue and oranges,blue and different shades of blue
I did look up some keywords for you...there are not any goods ones that I could find quickly.
THe best one,and it's not so good was 'carpet cleaning fayetteville nc'
it had a total monthly search of 590
It WAY beat out house cleaning fayetteville nc at 110
and cleaning service fayetteville nc at 70.
So, what I would do is use the better keyword as it will at least draw some attention to your site.
A nice amount of searches each month is a minimum of 1000 and up to around 4500. Alot more and it's too much competition ,less means there is not enough traffic,but then again you must go with what you are able to find. Just always use the best ones and then taper down from there.
NOTE: with photos, do not just load the photo onto the site.
What you want to do is name the photo your best keyword
For example: lets say you have a photo of office cleaners and you just plunk it in there and it's stored in the backend of your computer as cleaning photo number 10 or something.
Instead name it : carpet cleaning fayetteville nc
Why,because this is what googles search engines pick up on.
As well.DO NOT KEYWORD STUFF
Use the keyword in the title of the article, again on the first line of the article that you write and maybe ONE MORE TIME in the article. Anything more than say 4 is keyword stuffing and this is the sort of thing that gets you penalized.
(this is per article)
Your photo choices have zero to do with penalties.
Keep on looking for the best keywords you can find-takes a bit of word play,but you will find something you can use.Google keyword has a free tool.
I still think the facebook target ads are very good and super cheap.I use them for various sites and it's what provides the traffic to my sites.