I always have the best conversations while coming off of acid. And even if I am alone, I use every minute of my time returing from my subconscious to reflect on my life and my friends and family and the mysteries of the universe and how to better the world and myself etc.
There is clearner acid and there is poorer quality acid. Most good acid will be LSD-25, and if you're lucky you'll come across something like ALD-52, which is said to be smoother, so more of a posative body load where your senses intertwine rather than your body feeling tense. Poor quality acid doesn't nessicarily give you a bad trip if you enjoy acid, but a more physically uncomfortable feeling like jaw tension, back ache, stomache cramp. For newcomers, that alone can cause a bad experience because they feel warily and assume they may be in need of medical attention. Always good to trip with at least one experienced acid eater.
One time I was still slightly tripping in the afternoon, still coming off after tripping balls all night. I live in Arizona and summer afternoons are not pleasant. I felt like my brain was bleeding. Though I kept in mind acid is not physically harmful, I actually felt discomfort. I had to go around town cleaning swimming pools with my friend and I should have been home relaxing. Set and setting is everything. Just take care of your body on acid. For your first time trip in familiar places with close friends, good music, healthy light snacks, buddah (if you are a regular smoker, really enhances the visuals and lightens the mood). I like to eat fruit and play super mario brothers 3 while tripping :]