i see lots of people in sl still believe that a locked door is an answer to protect your home.
i can say to you:"its ISN'T!"

i still dont know if a costum securitysystem with radar/kicker can be beat.(the standard red banlines of sl arent )

but a locked door protects nothing. here is how i simply bypass the door within seconds.so i never "use" the door to enter the building
->
1.stand in front of the building
2. move your camera so you see indoor. look for something you could normally sit on (chair,couch, or even tv table or anything small)
3.rightclick the object and "sit here".
4. BAM, in most of the situations you sit on the object indoor without using the door. (doesnt work on any object because sometimes it will say, "no room to sit on")

the good thing of this cheat is you dont have to "rez" a prime lik some here do to enter an room(because you cant rez object in most of the sims)

so for you who has locked doors, sorry, they are worth nothing unless they have scanners with kickradius

i explained this for two reasons,
1. for people who like to explore'like me
2.for people who still believe they need locked doors so people couldnt enter

btw, this "cheat" works. i use it my hole life in sl to explore homes and private areas.(i only enter premisses if theres nobody home, i dont like to interfere in peoples lifes.)

good luck