Have heard of a number of these type of incidents and been warned to not go near the intake, you will be sucked into the engine etc.
On the strength of 2 bits of data I am a little suspicious of the being sucked in while walking around minding own business part.
1. Engine FOD of the center engine on B-727s understand from airline mechanics that this does sometimes happen and the objects are the usual junk lying around the taxiways and ramp. Incidence of FOD down dramatically with increase in distance from the a/c ahead. Conclusion/theory was that the a/c ahead would kick up the junk into the engine intake and FOD the engine.
2. Mid 1970s many a tale of crew being sucked into the intakes of A-7s (Bs and E's this is USN). A test was performed at NARF Jacksonville by spreading an area of a ramp with corn flakes. A-7 taxis over the cornflaked area and doesn't suck a one in. The exhaust rearranges them pretty good, but nothing sucked up in. Repeated at different power settings. Still no toasted cornflakes.
Conclusion: Unless you get up and in/in front of the engine intake you are (relatively) safe, but always treat these things with great respect.