Checking for spark

I am doing some diagnostics on an '85 190E that won't start. I want to first make sure I have spark, but the repair manual I have says to never crank the engine with the spark plug out of the engine. I have read posts that say to check for spark this way. What is everyones take on this? Can I check the coil by putting a spark plug on the wire that normally goes to the distributor cap?

Thanks
Dan

[Benzmac]

Your feeling is right. You can start the engine over without plugs in it, but the reason for the warning is you could ignite the fuel vapor that is lingering around in the combustion area. Be careful and you will be OK>

Yes, you can check for spark on the coil that way. ONe thing to remember, It might spark out of the head, but once under compression fail.

The reason is the spark will follow the least path of resistance.