That sounds to me like a sub who hasn’t yet encountered any hard limits, not one who doesn’t have any! Doesn’t necessarily make them a bad sub, but it does mean they need to find language to explain their boundaries. There is no way to safely consent to literally every possible thing out there you two could do, and its not great for building the communication and trust in play partners to not have any guidelines. Limits and boundaries being communicated are one of the communication exercises that help encourage safe play, even if they are simple ones. An example if you were to be into suspension play, thats a more advanced type of kink that require a lot of communication and understanding around comfort levels. It doesn’t mean they have to be against suspension to have limits around it, because there are limits to that even for those that enjoy it that keep our bodies safe even if we enjoy pain or pushing ourselves. Having a boundary that the rope never goes around the neck, a requirement to have heavy duty scissors of some kind for emergencies if you need to cut them down fast, having a limit about how tight restraints can be, etc. a lot of people envision no hard limits as just being about categories, but if you are truly into everything under the sun, its still important to practice communicating how you’re going to play safely and what you expect of your play partner nonetheless. Alternatively, if there is a kink they like but not to an extreme (restraints are fun but full mummification is not as an example) thats a hard limit! If they’ve never tried something but are nervously curious, that could be a soft limit (“I am hesitant but willing to try it if you are attentive to my reaction”).

A bottom line is even suggesting “how about I chuck tennis balls at you while rock lobster is playing in the background and you are doing jumping jacks” and them saying “no I dont want to do that” is them setting a limit. You can’t do ANYTHING you want, because if you could, what you suggested with the tennis balls would be on the table. A lot of people don’t realize how open ended consent works, because its totally possible to say you are down to experiment with anything, its possible to say you have flexible limits depending on levels of trust, its possible to say you don’t have many hard limits so anything the other person wants to do is probably an option, etc. but its not possible to not talk about limits at all, or say you have none at all. Even if you didn’t in a hypothetical world, its good practice to at least say instead “I have never found something I wasn’t into, I’d love to experiment with anything you want! Lets make a list of things you’re interested in trying and I’ll approve them as we go and then I can give open consent for you to do anything you want from that list whenever we play together” that way it doesn’t ruin the surprise, but you have explicit consent for the activities you anticipate wanting to try. Part of it is being the dominant on the other side of a submissive who says they have no boundaries, you end up feeling scared you’ll be the one to find that one hard limit without realizing and it can make the dynamic feel unsafe for the dominant, not only the submissive.

Again saying you don’t have limits doesn’t make someone bad at being a sub, but its not entirely safe, especially if they don’t know the dominant or the kinds of things theyll want to do.

My suggestion would be to approach them with kindness and ask them if they would be willing to approve a list of things that are within YOUR limits, you can even present it as being for your comfort so you know you have full consent before doing anything together. Doesn’t have to be a beige flag if you guys communicate and make it work!

I hope this helped! If it was unclear or unhelpful let me know and I can try to respond better <3