Hi , Please tell me is it a good idea I use my Google Adsense account for xxx site in case that I have tree other decent auto related sites with the same account ? And if I use it does this affects my already existing sites ads anyhow ? Thanks to all in advance !
No it is not a good idea, you will be banned as it is against Google TOS. It just take your competitor a simple report to Adsense to get you banned for life.
A definite no-no... Against Google's TOS. But you could use one of the ClickBank ad creation systems to add ClickBank-based products. But it depends on how much traffic you're getting as to whether this is worthwhile.