Maybe you remember the Johnny Walker whiskey advertisement showing the two Southampton mansions at night with one upper crust neighbor calling upon the other? The caption was, "I was hoping to borrow a cup of Johnny Walker Black"... Many of the prepper persuasion put great credence and faith in stockpiling tobacco an alcohol products which they expect will be items in great demand once retail vending of such items ceases.
Maybe they're right? Maybe their neighbors and strangers they wish to trade with will trade items which they possess, but the intrepid prepper forgot to purchase, all for a couple of airline bottles of liquor or a few cigarettes? Kinda doubtful.... See any holes in that rationale?
Perhaps the gentry of Southampton will trade their surgeon neighbor a case of Scotch or couple boxes of Partagas #10 churchills; but such doings will only be accommodations and an attempt to preserve civility. On the more common level, barter will hopefully facilitate trade. What will you offer the mechanic who can bypass a defective part and rig another salvaged from elsewhere to restore your generator or other important machine? Gonna offer him tobacco or liquor?
Any man who is head of household in all aspects once the collapse aftermath has settled-in, will be doing his family harm by trading valuable services, gear, or supplies for garbage that brings no value to his family. Does smoking or drinking bring any positive value to his family? Pretty had to rationalize that it does. Maybe you trade some oddball part you don't own equipment for and all the guy has is a bottle of Old Grandad? Maybe you know some retired Major of Marines who has the fondness for Old Grandad??? If so, it comes down to are you likely to get a better offer, and what can you trade into if you've got the bourbon?
Still, those who intend to profiteer off their neighbors addictions will find themselves regarded as something of a scourge. Imagine, the one chance in most smokers' lives to go cold turkey and the guy at the end of the block opens a smoke and bottle shop... Not a good business plan for building goodwill among families you have to live with.
What does work for barter? Things just about anyone can use and may need. Thing like electrical wire, replacement parts like outlets and switches, lightbulbs, matches, sewing needles, thread, first-aid items, aspirin, sunscreen, bug repellant, work gloves, socks, underwear, soap of all kinds, bleach, clothespins and clothesline, buckets, funnels, canned food, candy & treats, shoelaces and polish, used clothing like bluejeans and Carharrt dungarees, cooking oil and spices, dishpan sets with drying rack, DVDs and books, especially how-to and magazines.
Some of the most essential items might include flints and lighter fluid for Zippo lighters, a welding sparker and sparker fints, matches of all types, sharpening stones, files, Kitchen knives and utensils of all sorts, also flatware like forks and spoons. If you live rurally, maybe you have topo maps and cheap compass. Blank DVD and CDs also along with plain, ruled, and paper in binders.
You can buy specific items that're gonna bring more in a public barter, like individually wrapped TP or boxed soaps. Stuff in factory packaging shows item is original and not tampered with or shorted. Worth more in such situations. Yet, if you lay-in extra stock of most of the essentials you'll need, you'll have these things to offer others who might've not done so. If you have a Printer Refill Kit, you're gonna be a real pal to someone whose last inkjet cartridge had only a few print jobs left. Things like PVC pipe, plumbers glue, teflon tape etc enable much when needed and cost very little. A selection of hacksaw blades, cold chisels and files will enable a lot of metalworking projects and salvage. If you have a tap & die set or two you can be a real hero making screws and nuts that couldn't otherwise be replaced.
Buy good quality items and look for what is on sale or you can get savings by coupon. JoAnn Fabrics often has shopper coupons for up to 40% off. Maybe you buy a couple fabric wheel cutters and Gingher scissors and use one and put the other away?
Storing gasoline and other volatile fuels may be a concern, but you can buy extra oil, especially the high quality 2-stroke oil for chainsaws and other small engines, good synthetic grease and differential lube, along with brake fluid are also items many folks will have forgotten.
Not like you want to get known far and wide as a resource, but having extras and being willing to trade can be a real skill and blessing to your family and others.