We're not bothering, another way to cut back on a small budget...
I would if your budget allows for it... but it's not a big thing. Perhaps you can ask the reception hall to try and clean it up a little before your reception starts. It may not be attractive, but the least it should be is clean.
I'm including a bathroom basket with the essentials - if you get trial versions of things and search online for free samples, you can put together a bathroom basket for next to nothing. Instead of a flower arrangement, why not snag one or two potted plants you or a family member already has and use that to make the bathroom seem nicer. Other than that, if it's clean and doesn't smell, that's all you really need in a bathroom.
First of all, I would make certain that you speak with the venue "people" and definitely voice your concerns. People are going to be drinking which means lots of bathroom breaks. You don't want your guests to feel "dirty" after having been to the bathroom. You KNOW there will be someone who will make a comment. Bathroom baskets are a lovely idea and I would definitely do one. As erindira mentioned, trial sizes of things are best. Mouthwash, brush, perfume or body spray, hairspray, mints, gum, condoms, hand lotion, small sewing kit, clear nail polish for pantyhose runs, etc.
Here is my suggestion and it may be a little far fetched, but maybe bringing in a sort of designer that could dress up the bathroom a little.... maybe you can drape fabric to cover the walls, bring in candles to get rid of the smell if there is any.... and maybe a table that has a bathroom basket.... but yes def dress up the bathroom.... you dont want your guest walking away remembering the bathroom and not your wedding....
I would definitely include a bathroom basket and maybe a small arrangement to dress it up a bit. We're having a bathroom basket just for convenience. They can be done very cheaply.. i bought the basket 50% off at hobby lobby, and the insides- I'll be buying most of the things at Dollar Tree.. so maybe $15 total :)