2 questions about doggies

[UTUSN]

1) I've been companioned by six dogs over the years, and I've never made them do tricks in exchange for treats. I've hugged, played, petted, bathed, them, but never made them do the trick thing. I look for their natural behaviors, such as the curtsying thing. Treats, they get just because. Sometimes I wonder whether they are actually programmed to enjoy learning tricks and whether I have deprived them of something?

2) Something I've brought up as a question has actually SHOCKED a couple of people. Whenever I see the drug sniffer dogs, I wonder whether they are really ADDICTED. I mean, their sense of smell being so powerful, the mechanics of the drug ingestion... Wouldn't it make sense that they are actually getting HIGH? But then, what about the ones that sniff for vegetables or cadavers.