Australia and New Zealand are tough on quarantine (eg x-raying every bag for evidence of plant products, wooden items and a whole raft of other items) and issuing big penalties for false declarations. Customs tend to be ok, but sometimes some interesting questions.

But that doesn't stop me coming home (Australia) or visiting New Zealand. Some others here who have been on the wrong end of one of those infringement notices may have very unpleasant things to say though!

Most other countries I have visited have been ok. America really has been ok with generally pleasant immigration officers and straight through Customs. U.K tends to ask quite a few weird questions, but also is ok on the whole.

I spose it all depends on what you look like, your itinerary and a few other things. Any customs/immigration/quarantine officer can be very annoying if you get them on the wrong day...