The only thing inferior in a pigs senses are their eyesight. They have excellent hearing and a sense of smell to rival most dogs, but they are as blind as Ray Charles and Stevie Wonder.
Our family farm has been in the family approaching 130yrs. My great grandfather settled the place. In the mid to late 90s I told my dad that I was certain we had wild pigs in the river bottom pecan orchard. His response at the time was, I lived on this farm for close 60yrs and I have never seen a wild pig. Our property butted up to a 3500ish acres government piece of property and the north end of a major lake. I set up cameras, the old 35mm film ones, nothing. I put out bait, nothing. I even bought some of best you could afford at the time Gen 1 night vision, nothing. I decided to sit in the deer blind, even slept in it in hopes of figuring out what was eating the corn and sweet feed. Took about 3 - 4 nights and I finally shot a boar. I tried to drag it with my 4 wheeler, no dice. I finally went and got the front end loader and hauled it to the house. I showed my dad and his first words out of his mouth were, can you find me a revolver to carry when I go fishing. I killed a ton of pigs that year, I had recovered upwards of 90, shot 1/2 as many more and they still were as thick as thieves. I had Hamilton Meat Market process a ton of them, ended up buying 2 chest freezers for the meat. I gave away hundreds of pounds and even traded the processing fees for some of the donated sausage. The most impressive were two sows I shot and I ended up with 386lbs of ground breakfast sausage out of those 2. I was excited about it for about 2 months and then it got old quick. I refuse to eat them and I kill everyone I get a chance to.
You can have them in an area and when you realize what to actually look for, it can be very subtle at times, depending on what they are foraging on, it is too late.