Can spice be trusted?

it is well known that SPICE is used to verify our circuit's behavior.

but many times when i simulate one circuit the SPICE gives strange results such as jitter, overshoot, wrong value. but if i modify some options for the SPICE. the results show another value. then i continue to modify every option, again ang again, one, two, three, ....    finally the SPICE gives one result which is just my need.

now can i trust this results? i confused by SPICE. because this final result is based on the modified OPTIONS. if using other options the results is not accept.

so my question is if i tapeout my circuit???

who has experienceied? Pls help me.

thanks ywguo.

i have asked for the Spice company's engineer about this question. the answer is similar to your.