I was thinking about your recent experience going to a new provider with a sketchy incall location (despite its being described as nice) and I had a few thoughts for you.
-First, you can absolutely can where the provider will be hosting. While she may not know the exact hotel, it is likely she will know the general area; a quick google search or peek at booking.com or another hotel booking site should give you a broad indication of what you might expect.
-I feel like really high-end providers (highly rated among reviewers and with rates exceeding $400/hour) are likely to have nice incall locations. It is possible there could be the rare exception, but I for one fit into this category and I won't stay anywhere outside of downtown Boston nor will I book a hotel room that is fewer than 4 stars. Often I book 5 star hotels like the Ritz, the Four Seasons, the Taj, 15 Beacon (all in Boston) because I want to give my clients and outstanding and luxurious experience from the moment they walk in the door.
-Reviewers allude to the quality of the hotel room from time to time in the reviews. While each hobbyist's experience with a given provider may vary (hence the acronym YMMV) it isn't terribly often that clients describe the location at which they met said provider as being nice and the provider then staying somewhere shitty for you or other clients. If most clients describe the provider's chosen incall spots as being quite nice, you can assume that her selection for meeting you will also be nice.
-Lastly, if you are really worried about it, you can suggest a hotel and offer to pay the incremental difference between your choice and the average hotel (or the cost of another hotel you know she has stayed at). This will ensure that you are your choice of spots!
Hope this helps! To cut your lady a break, this past week hotels were a madhouse and she may have opted for a location she otherwise wouldn't have chosen because hotels that are 3+ stars were almost entirely full and therefore the asking price for a room was 2x what it normally would be.
There are some girls who work out of an apartment they rent for this express purpose (while wisely living in another apartment/house and/or town). If this is the case, you should be golden since you should know based on reviews what you are getting into prior to your arrival.
Hopefully this is an isolated incident and you will have better venues in the future. If not, you can always come up to Boston and see me. I'm happy to shell out an couple hundred extra to feel like I'm in a swanky, sexy setting