I think oil is checked for 2 main reasons: 1) Do I have enough oil? 2) Is the engine burning/leaking/using oil? The first question does not require great accuracy to answer. The second question does require accuracy. However, all it requires is repeatability. So the main point is which ever way you do it, always check it the same way. I have a level garage and always check it after it has sat overnight. As previously mentioned, just be glad you even have a dipstick!! I wonder which part they will remove next?

Mike

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra