It seems that you are aware that PC 17B allows a felony to be reduced to a misdemeanor, and this is done when someone typically files for an expungement of the criminal record. Expungement does not completely wipe out the charge on your criminal record, but there is a note on the record that the charge was reduced. After expungement, the record usually doesn’t come up in public searches. Although I don’t know the policies of the CA police dept, I can tell you that government agencies typically have access to the records even after they have been expunged.
PC 17(b) reduces a felony to a misdemeanor for "all purposes" with the following exceptions: 1) certain convictions which carry firearm bans will still prohibit you from owning or possessing a firearm; 2) strike convictions will remain strikes even if reduced; and 3) a 17(b) reduction does not change your obligation to register as a sex offender under PC 290 if that applies to your case.
Beyond that, anyone having authorized access to your criminal history will always see the original conviction. In applying for certain jobs, such as a policeman, your whole record will be available whether expunged or not.
California Government Code §1029(b)(2) says a person who has been convicted of a "wobbler" that can be a felony or a misdemeanor, and who successfully completes probation and gets the offense reduced to a misdemeanor, "shall not be disqualified from being a peace officer solely on the basis of the [conviction.]"
However, your criminal past will still raise some eyebrows in the selection process. Most offenses that can be charged as a felony, commonly known as "wobblers," involve dishonesty, drugs or violence... all traits that make someone an unlikely candidate to become a police officer. Even if your conviction doesn't automatically disqualify you, the character issues involved in your conviction might.
I don't understand why Ms. Hodjat thinks your conviction won't show up on a record search. An "expungement" only adds a notation to the court's public records, saying your case was dismissed after completion of probation; it does not seal the record. Anybody who knows where to look can find it, and many courts now have their records online.
That means criminal defense attorneys will know about your conviction and will likely raise the issue in any case where you testify. Even if it wasn't a public record, prosecutors would be required to disclose it to the defense. Your additional baggage makes you a far less desirable candidate than someone without a criminal history.