Many of the apps I've purchased for my Android phones over the years had a lite or ad-supported version for free and then a full version for purchase. I like being able to try something out first and when I have the option, I'm actually much more likely to pay for the full version. Ad-supported stuff is only good for testing out an app because they're annoying and obtrusive but I can understand having them in free/demo versions. If the only thing that sucks about a useful app is the ads, I'll gladly pay to get rid of them.

Then there's the demo stuff where you pay to unlock extended features. Sometimes I don't necessarily need those (like on the Hue Pro app or Nova Launcher) but when I use something daily and it's $1.99 to get the full version, I tend to buy "pro" more often than not. It's more a matter of maybe wanting the extra functionality or wanting to support the dev than about necessity in most cases but it definitely beats having to buy something only to find out it's crap.

If anything, the only reason I skip an app entirely is because I can't find enough trusted info to convince me it's something I want and there's no free version to test out first. Only for trusted devs and well-known and thoroughly reviewed apps do I tend to buy without a trial/demo first.