They are strict on certain items (mainly food), they only hand search if they are suspicious about the bags. All bags are x-rayed after baggage carousel.
Best advice: If bringing food declare it, better to have something confiscated than face automatic fines and a grilling by AU customs. Packaged foods (with intact seals) are usually allowed if they can see the ingredient list.
Do not bring: milk products, meat products
Can bring if declared: wood products, non-perishable foods if in original packaging with ingredient list on sticker.
Toiletries are allowed in checked baggage and small amounts (i.e. 50 ml sizes) are allowed in carry on baggage if packed in a clear plastic bag (for inspection).
Do not bring nail clippers, scissors in carry baggage as those will be confiscated. Read the airline baggage policy in detail (especially carry on baggage before you start packing).