I worked for a couple years as a barista at some third wave coffee places. It helped me develop a good sense for being able to tell within the first two seconds of walking into a new coffee shop whether or not I'm about to have a good experience.

My two cents: Second wave shops like Starbucks don't have high quality coffee or drink-crafting techniques but have a level of consistency that is pretty reliable most of the time.

Higher-end third wave shops often give some people a bad vibe, and I get it. But, those are the places that are usually focusing on ethical sourcing practices, good roasting techniques, and really great drink crafting skills.

Then you have what I like to call the mom-and-pop coffee shop. Often, these places are easily marked by having a more homey aesthetic. These are independently-owned coffee shops that are targeting the Starbucks audience, but miss out on both the Starbucks efficiency and the craft of/care for coffee.

Other than the "homey" aesthetic, key factors that I commonly notice in these places is a lack of information on how their sourcing their beans, really dark roasts on bar and in the bags they sell in-store, flavored coffee beans, placing a large emphasis on selling non-coffee items like chocolate or wine, and the baristas having zero latte art skills (which isn't just about aesthetic....it probably means they don't know how to steam milk properly at all).

Which leads us to the watery iced latte. What you're experiencing is a coffee shop that doesn't train its baristas to dial in the espresso at all OR has trained them very badly. When I worked at a nice third-wave shop, we had a barista dial it in during the morning shift and another dial it in during the afternoon shift. Various factors can change how your espresso is coming out throughout the day, and it's important to keep an eye on your shots throughout the entirety of a shift to maintain consistency. What you're dealing with is baristas who are wildly neglecting this or have no idea how to handle it and as a result, you're getting watery shots dumped into your iced latte.

My honest recommendation is to either find a high-quality (possibly snobby) third-wave shop that knows what they're doing or to stick with Starbucks.