Use coin control. Spend an output that is very close in value to what you are sending.
Yeah what I meant is, due price fluctuations and tx fees, some amount may be left there. Let's say you have 200 bucks left spend on your Android, and you want to buy something that costs 200, you basically have to add in an extra 100 because the price may dump by the time you arrive to the meeting to exchange the item or service for your BTC, plus fees. You always have to add this extra margin.
Now you're taking it into an extreme case. What are the odds you have the exact amount you need to pay in your mobile wallet? And what are the odds of Bitcoin dropping 33% during the time it takes you to make the trade?
I'd worry much more about showing my actual face than exposing one of my UTXOs to a seller.
If you have 200 and the price goes up a bit, and you have like 220, so you pay 200 + fee, perhaps there's like 10 bucks left or so, so you left 10 here and there, end up with a decent amount in different addresses, which if you wanted to consolidate into a single one, would mean that you compromise your privacy since you send a joined transaction with all of these.
You can send small change to an instant exchanger, or use it to top-up a hosting or VPN account. Or just keep it long enough for it's value to skyrocket.
I want to have a reasonable privacy, and when it comes to authorities, you just want to avoid raising any flags because they hate crypto by default.
Here, they don't hate crypto. As long as you pay your taxes, you're good.
In my jurisdiction, I find that the biggest inconvenience is the need to keep track of every satoshi acquired and spent so I can report every single transaction when calculating my capital gains for my taxes every year.
I don't have to do that. All I do, is pay 2.1744% tax (per year) on all Bitcoin I own. You have no idea how lucky you are, I'd gladly exchange for a capital gains tax with additional paperwork.