You can scam gangs and plan robberies on them, however, this is not to be abused.
Example: Do not rob everyone or every gang every 10 minutes. Any gang seen overusing this will be considered bad RP.
The RP behind any scam must be built up and planned out, not done just for the sake of doing something. This will be monitored by staff.
If the RP behind a scam is good, there is no limit on what you can rob.