Regardless of the supplier I always check the car before I drive off - pitch black, pouring with rain - whatever. In most of the compounds there is a lighted area even if just for security lighting. If all fails I make them come out with a torch (only once!)
Don't trust any of them an inch is my view.
I once collected a car from Europcar which was supposedly in perfect condition. When I drove it to a lighted area to check, virtually the whole length of the passenger side had been scraped to the extent that the trim was knocked off. Did they apologise? Not likely!
As far as Hertz is concerned I have had some minor damage occasionally and they have not bothered about it (so far). I don't always use them - I often book via Holiday Autos if they have a significantly cheaper deal - but have had no problem to date. In addition I take out an annual damage waiver policy with http://www.insurance4carhire.com/ and that covers me for any damage, including that which is generally excluded by the damage waiver policies which the car hire people sell - e.g windscreen. At a cost of £49 for Europe it costs me less than insuring each time (even with Holiday Autos at £2.50 per day) given the number of times I hire a year.
If there is not too much in the price I tend to go for Hertz as the No 1 Club service is excellent. Last time I hired from them (Oct at Toulon) I had the car keys and was on my way in less than 2 minutes!!
PS I have no connection with ANY of the businesses mentioned here!!!