Last night I scheduled and appointment but when I got to the provider's location
she was late and made me wait for quite some time. I was nice enough to wait for her. The whole thing turned to be a bad experience as her attitude wasn't as I expected. Can you all think of any clues we can keep in mind to avoid rip offs or just bad providers?

I mean, knowing that she was late and that she did not have a good attitude as soon as I came in, I should had said I had forgotten something, canceling the appointment.

If they don't welcome you in a way you feel comfortable then why spend our time with them.

advice I was given when I first started hobbying:

Stick to well reviewed escorts.

eme has a point...better to stick with people who have solid reviews.  I have been caught going by great pics and suggestive intros only to be stuck.

Also, be very careful to judge on your own criteria.  If the pics don't match the hostess or the vibe ain't right -- do NOT force it.  

It's hard when you're new to the hobby...but find your best experience and demand something in that ballpark.  I'm not saying every next girl is gonna top the one before her...but you need to set a standard for yourself.  If the opening "hello" is a bad WTF moment...if you continue it becomes on you.

Just the same way girls/agencies expect you to provide verification or references...you should insist on a hostess who has her stuff in check too.

I have had good experiences from providers that met at least one of the following criteria.

1. They had good reviews themselves.  OR
2. They were recommended by other well reviewed providers OR
3. They worked for reputed agencies.

I would give higher importance to doing your own homework than relying on other people's or agency's recommendations.  

That being said still keep in mind that YMMV - Your Mileage May Vary, and is based on your chemistry with the lady.  No amount of homework can eliminate this risk.

Given the bad experience you had, I would submit a review so that others will be able to avoid her.

this also happens with well reviewed providers, and I can think of two off the top of my head.

It happens. I never wait. I arrive a few minutes before and call. I give a max five minute response time. If they call and ask for more time, I NEVER go 15 more than minutes past my scheduled time UNLESS I know very her well and have the time. Ad that is only if she calls. If I know the provider I might give her more than five minutes to respond to my call (but not more than 15).

I check my watch. When the second hand tells me it's time to go, I leave. I do not turn around even if she calls as I am headed out the parking lot. I MIGHT turn around (if I am very close) if she is calling with the room number, but I am still very likely to say I have already left. I try not to be swayed by offers of discounts if I return, but maybe if I know her.

I am a client, and she is a service provider. I am NOT an ATM, nor will I be treated as such. Rewarding bad service with business only fosters further bad behavior.

IF I choose to go back, I am clear in my mind that I made the choice to go back, and I am prepared to leave if things don't appear to be going well from the moment I step in the door. Whenever I choose to stay, that is my choice and if it doesn't go well, I only have myself to blame and a bad review to write (but don't make it personal).

be prepared to walk away.  If you deal the non-TER reviewed, expect around half to be total duds.  But consider this: For me at least, my interest in hobbying is significantly satisfied by everything leading up to the appointment with a provider (the emailing, the calling, etc.)...the moments of anticipation are often as fun as the actual meeting.  Once I learned to embrace and enjoy the prelude, I have found it much easier to walk away when I get a bad feeling or at least to accept a subpar meeting.

Just like we you have to "do your homework" but that's half the battle....some can be ymmv but if you're getting treated that way for no reason just do a fast u-turn.