I occasionally get the impression that advertising having more JavaScript experience than something like Python automatically creates a negative impression. Is it just me or does that perception exist?
A business owner who's going to pay you is going to pay you because you deliver something they need but can't find cheaper elsewhere. Almost every business needs some form of web frontend - even mobile-first businesses often need good webapps for marketing & administration purposes. The disdain and loathing from some of the rest of the developer community actually works in your favor, most of the time: it keeps competition out or makes them ineffective at learning the skills needed to be effective.
The one thing to watch out for is that frontend technologies typically have a very short lifetime: in 4-5 years, much of what makes you valuable may be obsolete, and work in it tends to dry up. Just ask DOS/assembly devs in 1995, Swing or MFC developers in 2006, or basic PHP/Rails/Wordpress webdevelopers now. Be prepared to keep learning, and focus on general principles like good UI design, responsiveness, latency, managing state, MVC/MVP architectures, etc.
Node may be turning the perception of JS, but it is a slow process. Node is still very young. It's community is still highly focused on building the tooling, while the community around a more mature language like Python has long since found its voice. Right now, Node is seen as a chaotic mess for web devs that are forced to do back end work because management thinks a code monkey is a code monkey and doesn't want to pay for the vastly more expensive systems devs. (To be fair, a little start up likely doesn't have enough of a customer base to require that level of performance tuning.)
Python devs are usually seen as academics, more experienced, and very mathematically inclined. But there was a time when Python was the kiddie language because it abstracts away so many details. Now it is the majority language for machine learning, which is a very hot trend.
Once the toolsets stabilize, Node developed a robust multi-threaded model on the server, and it actually solves an engineering problem better than any other language, you may start seeing more engineers picking JS as a tool. Till then, it will just be the hip startup toy used to interest young CS grads that the companies will have to rip out later to continue scaling.
I am one of those folks that specialize in JS and admittedly, the freedom of the syntax can lead to some pretty poor code. I suppose that's why most "serious" projects have resorted to bolting on type checking systems.
In all depends on where you stand.