Apparition & Fidelius

[maidne]

No: HPFGUIDX 90953

Here's what I want to know about Fidelius:  No one can see the house 
without the secret keeper's help, right?  But they can see someone 
standing on the sidewalk, prior to approaching the house.  At what 
point does the entering person disappear?  When they step onto the 
front step, or not until the door is answered and they enter the 
house?  Either way, it seems like someone, at some point, would see 
someone disappear off the street and wonder what was going on.  A 
nosy muggle neighbor (like Petunia) might even notice this 
repeatedly, and that knowledge could be obtained and used by 
unscrupulous parties.

Susan