Are phone app spectrum analyzers accurate?

I'm constantly amazed at the cool things a smart phone can do.  There are several spec. analyzer apps available but I'm wondering if they're really accurate enough to use for system tuning?  I've tried a couple of these and I like Speedy Spectrum and Spectrum Analyze (for android) the best for features and apparent accuracy.
My old Heathkit portable analyzer looks to be toast (yeah--I'm that old).

What are the thoughts from the hive?
Any analyzer can only be as accurate as it's microphone allows.   Good analyzers/DSP room correction systems come with calibrated mics.    One has to wonder what the frequency curve might look like, of a telephone's mic.
RTA Audio and Audio Tool apps work great for home audio use, and are calibrated for the iPhone microphone.
I use RTA for a rough guide. It seems to match up pretty closely with the hi-tech program my dealer used to calibrate my DSP.

Genelec Speaker Angle is useful to align your speakers.
Calibrated for the iPhone? Which model?

Any app could equalize a cheap mic--but the apps don't ask what phone it's installed on, don't have a calibration feature, and don't have a differential mode.
RTA paid version has a calibration feature.
They are as good as there mic's, which in most phones is pretty poor.  Also, if the mic is not calibrated, the results you get can be misleading. So, in the end it really depends on what you are using the app for.  Certainly the results could not be called 'professional' standards.