I bought a three pack about 5 years ago and am only on the 2nd can. They're great for a very occasional spritz into a fan or some other dusty region when you have a laptop or desktop open for a repair.
Otherwise I'll use a vacuum or duster, if it's not delicate electronics.
Uh, that's not true at all. CFC's that most people are concerned with emitting aren't necessarily greenhouse gases, and the greenhouse contribution is not really a primary concern with them.
The primary concern is that many of them are catalysts with very very long active lifespans. As a catalyst (not a consumable reactant), a single CFC molecule is capable of destroying hundreds of thousands of ozone molecules in the upper atmosphere (or more). It's the catalytic nature that makes these things problematic and accumulative even in small amounts. The accumulation of these long-lived gasses would be measurable if everyone were blasting their laptop once a day, which is precisely why a number of them are banned completely. The ones generally used now are relatively better, but there is still plenty of reason to avoid emitting them if possible.
Cigarette smoke isn't comparable when it comes to environmental concern, nor are most common combustion byproducts. Those definitely cause concern for different reasons, but aren't directly comparable to environmental concerns raised by CFCs.
I have had great success cleaning using a electronics vacuum. It is a type of vacuum that blows instead of sucks and uses non-conductive materials to avoid static discharge.
I got one for around 60 USD and unless the motor breaks it should last forever. There are also screen and electronic safe wet wipes for cleaning phones and other messes that a vacuum would not solve.
